1
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Guzman AL, Kevorkian PV, Hoye TR. 2:1 Adducts Arising from Reactions between Benzynes and 1,3,4-Oxadiazoles. Org Lett 2024; 26:3834-3839. [PMID: 38686996 DOI: 10.1021/acs.orglett.4c01005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2024]
Abstract
2:1 adducts arise from the reaction of 2,5-diaryl-1,3,4-oxadiazoles and benzynes generated from the hexadehydro-Diels-Alder (HDDA) reaction. Density functional theory computations support a mechanistic manifold that includes a concerted SNAr process. Additionally, the benzyne trapping reaction of 2,5-dimethyl-1,3,4-oxadiazole affords an unusual acylimine-containing 2:1 adduct, which is the first case in which a dearomatized product has arisen from a HDDA reaction.
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Affiliation(s)
- Alexander L Guzman
- Department of Chemistry, University of Minnesota, 207 Pleasant Street Southeast, Minneapolis, Minnesota 55455, United States
| | - Paul V Kevorkian
- Department of Chemistry, University of Minnesota, 207 Pleasant Street Southeast, Minneapolis, Minnesota 55455, United States
| | - Thomas R Hoye
- Department of Chemistry, University of Minnesota, 207 Pleasant Street Southeast, Minneapolis, Minnesota 55455, United States
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2
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Kevorkian PV, Sneddon DS, Ritts CB, Hoye TR. Phosphorane-Promoted C-C Coupling during Aryne Annulations. Angew Chem Int Ed Engl 2024; 63:e202318774. [PMID: 38324736 PMCID: PMC11002863 DOI: 10.1002/anie.202318774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Revised: 01/13/2024] [Accepted: 01/15/2024] [Indexed: 02/09/2024]
Abstract
Arynes are fleeting, high-energy intermediates that undergo myriad trapping reactions by nucleophiles. Their unusual reactivity compared to other electrophiles can spur unexpected mechanistic pathways enroute to the formation of benzenoid products. Herein we explore a particularly unique case of thermally generated arynes reacting with phosphoranes to form helical dibenzothiophenes and -selenophenes. Multiple new helical polycyclic aromatic products are reported. DP4+ and X-ray crystallographic analysis were used in tandem to confirm the structural topologies of selected products and to demonstrate the utility of DP4+ for distinguishing between isomeric polycyclic aromatic compounds. Lastly, we discuss a plausible mechanism consistent with DFT computations that accounts for the product formation; namely, ligand coupling (i.e., reductive elimination) within a hypervalent, pentacarbon-ligated σ-phosphorane furnishes the dibenzothio- or dibenzoselenophene.
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Affiliation(s)
- Paul V Kevorkian
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, MN 55455, USA
| | - Dorian S Sneddon
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, MN 55455, USA
| | - Casey B Ritts
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, MN 55455, USA
| | - Thomas R Hoye
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, MN 55455, USA
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3
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Martins LMOS, Souto FT, Hoye TR, Alvarenga ES. Deciphering molecular structures: NMR spectroscopy and quantum mechanical insights of halogenated 4H-Chromenediones. Magn Reson Chem 2024. [PMID: 38557999 DOI: 10.1002/mrc.5445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 02/15/2024] [Accepted: 03/13/2024] [Indexed: 04/04/2024]
Abstract
Sesquiterpene lactones (SL) represent a class of secondary metabolites found in the Asteraceae family, notable for their unique structures. The SL α-santonin (1) and its derivatives are worthy of mention due to their diverse biological properties. Additionally, 4H-chromenes and 4H-chromones are appealing frameworks holding the capability to be used as structural motifs for new drugs. Furthermore, unambiguous structural elucidation is crucial for developing novel compounds for diverse applications. In this context, it is common to find in the literature molecules erroneously assigned. Therefore, the use of quantum mechanical calculations to simulate NMR chemical shifts has emerged as a valuable strategy. In this work, we conceived the synthesis of two halogenated 4H-chromenediones derived from photosantonic acid (2), a photoproduct arising from irradiation of α-santonin (1) in the ultraviolet region. The structure of the chlorinated and brominated products was determined by NMR analysis, with the aid of quantum mechanical calculations at the B3LYP/6-311 + G(2d,p)//M062x/6-31 + G(d,p) level of theory. All analyses were in agreement and led to the assignment of the brominated 4H-chromene-2,7-dione as (3S,3aS,5aR,9bS)-5a-(2-bromopropan-2-yl)-3-methyl-3,3a,5,5a,8,9b-hexahydro-4H-furo[2,3-f]chromene-2,7-dione (11b) and of the chlorinated 4H-chromene-2,7-dione as (3S,3aS,5aR,9bS)-5a-(2-chloropropan-2-yl)-3-methyl-3,3a,5,5a,8,9b-hexahydro-4H-furo[2,3-f]chromene-2,7-dione (12b). The diastereoselectivities of the reactions were explained based on products and intermediates formation energy calculated using B3LYP/6-31 + G(d,p) as the level of theory. Structures 11b and 12b were identified as the thermodynamic and kinetic products of the reaction among all candidates. Consequently, the strategy utilized in this study is robust and successfully illustrates the use of quantum mechanical calculations in the structural elucidation of new compounds with potential applications as novel drugs or products.
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Affiliation(s)
- Lucas M O S Martins
- Department of Chemistry, Universidade Federal de Viçosa, Viçosa, MG, Brazil
- Chemistry Institute, Universidade de São Paulo, São Paulo, SP, Brazil
| | | | - Thomas R Hoye
- Department of Chemistry, University of Minnesota, Minneapolis, MN, USA
| | - Elson S Alvarenga
- Department of Chemistry, Universidade Federal de Viçosa, Viçosa, MG, Brazil
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4
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Xu Q, Hoye TR. A Cascade of Strain-Driven Events Converting Benzynes to Alkynylbenzocyclobutenes to 1,3-Dien-5-ynes to Cyclic Allenes to Benzocyclohexadienones. J Am Chem Soc 2024; 146:6438-6443. [PMID: 38437506 DOI: 10.1021/jacs.3c10225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/06/2024]
Abstract
Here, we report a strain-promoted cascade reaction that proceeds via multiple strained intermediates, ultimately driven by the high potential energy inherent in alkyne triple bonds (C≡C). More specifically, four alkynes (three from an HDDA benzyne precursor and the fourth from a conjugated enyne reaction partner) are transformed into eight of the skeletal carbons in the benzocyclohexadienone products. The reaction pathway proceeds sequentially via strained benzyne, benzocyclobutene, and cyclic allene intermediates. DFT computations suggest that the slowest step following benzyne generation is the 4π-electrocyclic ring-opening of the alkynylbenzocyclobutene to a 1,3-dien-5-yne (an alkynylxylylene) intermediate. The activation energy for the subsequent 6π-electrocyclic ring-closure is lower than that for related acyclic dienynes because of the aromaticity that is being regained in the transition structure. Finally, the isolation of the benzocyclohexadienone products rather than their phenolic tautomers is notable.
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Affiliation(s)
- Qian Xu
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, Minnesota 55455, United States
| | - Thomas R Hoye
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, Minnesota 55455, United States
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5
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Kaicharla T, Lee S, Wang R, Pehere AD, Xu S, Hoye TR. Novel Conversions of a Multifunctional, Bio-sourced Lactone Carboxylic Acid. ARKIVOC 2023; 2:202312081. [PMID: 38361761 PMCID: PMC10869105 DOI: 10.24820/ark.5550190.p012.081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2024] Open
Abstract
The plant-derived compounds furfuryl alcohol and itaconic anhydride are known to undergo a Diels-Alder reaction at room temperature and in bulk to efficiently give an alkene-containing lactone carboxylic acid. Reported here is the conversion of this substance to a variety of derivatives via hydrogenation, epoxidation, or halolactonization reactions. Most notable is the formation of a set of three related acrylate or methacrylate esters (see graphical abstract) produced by direct acylative ring opening of ether bonds using Sc(OTf)3 and (meth)acrylic anhydride. These esters are viewed as promising candidates for use as biorenewable monomers in reversible addition-fragmentation chain transfer (RAFT) polymerization reactions.
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Affiliation(s)
- Trinadh Kaicharla
- Department of Chemistry, 207 Pleasant St. SE, University of Minnesota, Minneapolis, MN 55455 USA
| | - Sangjun Lee
- Department of Chemistry, 207 Pleasant St. SE, University of Minnesota, Minneapolis, MN 55455 USA
| | - Ruiqin Wang
- Department of Chemistry, 207 Pleasant St. SE, University of Minnesota, Minneapolis, MN 55455 USA
| | - Ashok D Pehere
- Department of Chemistry, 207 Pleasant St. SE, University of Minnesota, Minneapolis, MN 55455 USA
| | - Shu Xu
- Department of Chemistry, 207 Pleasant St. SE, University of Minnesota, Minneapolis, MN 55455 USA
| | - Thomas R Hoye
- Department of Chemistry, 207 Pleasant St. SE, University of Minnesota, Minneapolis, MN 55455 USA
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6
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Kraemer N, Eason EM, Hoye TR. Intramolecular Cyclization of Alkynylheteroaromatic Substrates Bearing a Tethered Cyano Group: A Strategy for Accessing Fused Pyridoheterocycles. J Org Chem 2023; 88:12716-12726. [PMID: 37590897 DOI: 10.1021/acs.joc.3c01411] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/19/2023]
Abstract
Heterocyclic substrates containing a conjugated alkyne and a pendant nitrile were shown to cyclize in an overall tetradehydro-Diels-Alder reaction to give products in which the initial heterocycle bears a newly fused pyridine ring. Base-promoted tautomerization of the alkyne to its isomeric allene allows this process to occur at ambient temperature. DFT studies support many of the mechanistic interpretations of the overall results.
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Affiliation(s)
- Niklas Kraemer
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, Minnesota 55455, United States
| | - Erin M Eason
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, Minnesota 55455, United States
| | - Thomas R Hoye
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, Minnesota 55455, United States
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7
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Sneddon DS, Hoye TR. The contrasting reactivity of trans- vs. cis-azobenzenes (ArN[double bond, length as m-dash]NAr) with benzynes. Chem Sci 2023; 14:6730-6737. [PMID: 37350825 PMCID: PMC10284128 DOI: 10.1039/d3sc02253f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Accepted: 05/25/2023] [Indexed: 06/24/2023] Open
Abstract
We report here a study that has revealed two distinct modes of reactivity of azobenzene derivatives (ArN[double bond, length as m-dash]NAr) with benzynes, depending on whether the aryne reacts with a trans- or a cis-azobenzene geometric isomer. Under thermal conditions, trans-azobenzenes engage benzyne via an initial [2 + 2] trapping event, a process analogous to known reactions of benzynes with diarylimines (ArC[double bond, length as m-dash]NAr). This is followed by an electrocyclic ring opening/closing sequence to furnish dihydrophenazine derivatives, subjects of contemporary interest in other fields (e.g., electronic and photonic materials). In contrast, when the benzyne is attacked by a cis-azobenzene, formation of aminocarbazole derivatives occurs via an alternative, net (3 + 2) pathway. We have explored these complementary orthogonal processes both experimentally and computationally.
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Affiliation(s)
- Dorian S Sneddon
- Department of Chemistry, University of Minnesota 207 Pleasant St. SE Minneapolis MN 55455 USA
| | - Thomas R Hoye
- Department of Chemistry, University of Minnesota 207 Pleasant St. SE Minneapolis MN 55455 USA
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8
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Yuan J, Anantharamkrishnan V, Hoye TR, Reineccius GA. Covalent Adduct Formation between β-Lactoglobulin and Flavor Compounds under Thermal Treatments That Mimic Food Pasteurization or Sterilization. J Agric Food Chem 2023. [PMID: 37278577 DOI: 10.1021/acs.jafc.3c01220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Thermal processing (e.g., pasteurization and sterilization) is a critical step ensuring the microbial safety of our foods. Previous work from our laboratory has examined the covalent reactions occurring between proteins and a broad selection of flavor compounds under ambient storage temperatures (25-45 °C). However, similar research on reactions of flavor compounds with a protein under thermal processing conditions has not been investigated. In the current study, covalent adduct formation between β-lactoglobulin (BLG) and 46 flavor compounds encompassing 13 different classes of functional groups was investigated under pasteurization and sterilization conditions by UPLC-ESI-QTOF-MS. BLG was chosen as a representative protein for this study because it is structurally well characterized, its molecular weight is well suited for ESI-MS analysis (18.2 kDa), and it is broadly used in the food industry. Schiff base, aza-Michael addition, and disulfide linkages were the main types of covalent interactions occurring across the reactive samples. Among them, isothiocyanates, aldehydes, and thiol-containing compounds were generally very reactive. Increasing the severity of the thermal treatment [high-temperature-short-time (HTST) pasteurization, in-container pasteurization (IC), and ultra-high-temperature (UHT) sterilization conditions] accelerated the reactions of BLG with flavor compounds, which revealed reactivity of three flavor compounds not previously observed to react at room temperature (eugenol, 4-vinyl phenol, and 3-nonen-2-one). Ketones [other than 2-hydroxy-3-methyl-2-cyclopenten-1-one (cyclotene), diketones, and unsaturated ketones], alcohols, acids, alkenes (terpenes), esters, lactones, 3-acetylpyridine, methyl anthranilate, vanillin, 2-methylthiophene, and dimethyl sulfone did not show measurable reactivity with BLG under the thermal processing conditions examined. An overall view of the data shows that the HTST heat treatment (72 °C for 15 s) had the least effect on the extent of reaction while in-container pasteurization conditions (63 °C for 30 min) produced a similar extent of reaction as the UHT (130 °C 30 s) heat treatment. These varying extents of adductation are in reasonable accord with what one might expect, given that the rates of most classes of chemical reactions occurring near ambient temperature increase by a factor of 2-4 for each increase of 10 K in temperature. Unfortunately, our methodology did not permit us to obtain meaningful data using the most aggressive standard sterilization thermal conditions (110 °C for 30 min) because extensive aggregation/coagulation removed essentially all of the BLG protein from the reaction mixtures prior to MS analysis.
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Affiliation(s)
- Jieyao Yuan
- Department of Food Science and Nutrition, University of Minnesota, St. Paul, Minnesota 55108, United States
| | | | - Thomas R Hoye
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Gary A Reineccius
- Department of Food Science and Nutrition, University of Minnesota, St. Paul, Minnesota 55108, United States
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9
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Abstract
Strained cyclic allenes are reactive species that can be trapped in a variety of complementary fashions that capitalize on their inherent high potential energy. 1,2,4-Cyclohexatrienes represent a subclass of allenes that, notably, can be conveniently generated by a net [4 + 2] cycloaddition within a 1,3-enyne bearing a tethered alkyne via a tetradehydro-Diels-Alder reaction. A limitation to the use of this type of thermally generated cyclic allene as a construct for the introduction of molecular complexity is their propensity to isomerize to benzenoids via a simple net 1,5-hydrogen atom migration. We have discovered that when the enyne component of the substrate is modified as an enol silyl ether (or an enol ester), migration of the silyl (or acyl) group can become the predominant event. Specifically, an appropriately electrophilic group can migrate from the O atom to the central allene carbon adjacent to the 1-siloxy(acyloxy) substituent. This process leads to highly substituted phenolic products (e.g., o-silyl phenols) following tautomerization of the intermediate cyclohexa-2,4-dienone. Experimental studies show that this novel mode of reactivity is general; DFT studies reveal the unimolecular nature of the group migration.
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Affiliation(s)
- Qian Xu
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, MN 55455, United States
| | - Thomas R. Hoye
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, MN 55455, United States
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10
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Abstract
The presence of a nearby tethered functional group (G, G = tertiary amide or amine) can significantly impact the rate of cleavage of an Si-O bond. We report here an in situ 1H NMR spectroscopic investigation of the relative rates of cleavage of model substrates containing two different Si-O substructures, namely alkoxydisiloxanes [GRO-Si(Me2)-O-SiMe3] and carbodisiloxanes [GR-Si(Me2)-O-SiMe3]. The trends in the relative rates (which slowed with increasing chain length, with a notable exception) of alkoxydisiloxane hydrolyses were probed via computation. The results correlated well with the experimental data. In contrast to the hydrolysis of the alkoxydisiloxanes, the carbodisiloxanes were not fully hydrolyzed, but rather formed an equilibrium mixture of starting asymmetric disiloxane, two silanols, and a new symmetrical disiloxane. We also uncovered a facile siloxy-metathesis reaction of an incoming silanol with the carbodisiloxane substrate [e.g., Me2NR-Si(Me2)-O-SiMe3 + HOSiEt3 ⇋ Me2NR-Si(Me2)-O-SiEt3 + HOSiMe3] facilitated by the pendant dimethylamino group, a process that was also probed by computation.
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Affiliation(s)
- Ethan A Gormong
- Department of Chemistry, University of Minnesota, 207 Pleasant St, SE, Minneapolis, Minnesota 55455, United States
| | - Dorian S Sneddon
- Department of Chemistry, University of Minnesota, 207 Pleasant St, SE, Minneapolis, Minnesota 55455, United States
| | - Theresa M Reineke
- Department of Chemistry, University of Minnesota, 207 Pleasant St, SE, Minneapolis, Minnesota 55455, United States
| | - Thomas R Hoye
- Department of Chemistry, University of Minnesota, 207 Pleasant St, SE, Minneapolis, Minnesota 55455, United States
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11
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Jin M, Hoye TR. Lactone Ring-Opening Equilibria in Methanol by 1H NMR Analysis: An Assessment of the Ring-Opening Polymerizability of Lactone Monomers. Macromolecules 2023. [DOI: 10.1021/acs.macromol.2c01141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- Mengyuan Jin
- Department of Chemistry, University of Minnesota, 207 Pleasant Street, SE, Minneapolis, Minnesota 55455, United States
| | - Thomas R. Hoye
- Department of Chemistry, University of Minnesota, 207 Pleasant Street, SE, Minneapolis, Minnesota 55455, United States
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12
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Xu Q, Hoye TR. Electronic Character of α,3-Dehydrotoluene Intermediates Generated from Isolable Allenyne-Containing Substrates. Angew Chem Int Ed Engl 2022; 61:e202207510. [PMID: 35965409 PMCID: PMC9529817 DOI: 10.1002/anie.202207510] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Indexed: 01/05/2023]
Abstract
We report here the generation of α,3-dehydrotoluenes, a relatively rare subset of reactive intermediates of the dehydroaromatic family, from isolable allenynes. The substructure motif in the allenyne substrates is distinct from, and complementary to, those found in Myers-Saito/Schmittel-type cycloisomerizations. The reactions reported here give rise to product profiles that provide insight about the electronic nature (i.e., diradical vs. zwitterion vs. cyclic allene) of the particular isomeric DHT(s) that is(are) produced under different reaction conditions differing most significantly in the polarity of the reaction solvent. One example also revealed previously unobserved carbene-like reactivity of the DHT.
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Affiliation(s)
- Qian Xu
- Department of ChemistryUniversity of Minnesota207 Pleasant St., SEMinneapolisMN 55455USA
| | - Thomas R. Hoye
- Department of ChemistryUniversity of Minnesota207 Pleasant St., SEMinneapolisMN 55455USA
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13
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Xu Q, Hoye TR. Electronic Character of α,3‐Dehydrotoluene Intermediates Generated from Isolable Allenyne‐Containing Substrates. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202207510] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Qian Xu
- Department of Chemistry University of Minnesota 207 Pleasant St., SE Minneapolis MN 55455 USA
| | - Thomas R. Hoye
- Department of Chemistry University of Minnesota 207 Pleasant St., SE Minneapolis MN 55455 USA
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14
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Kaicharla T, Chinta BS, Hoye TR. Examples Showing the Utility of Doping Experiments in 1H NMR Analysis of Mixtures. J Org Chem 2022; 87:5660-5667. [PMID: 35442679 PMCID: PMC9583569 DOI: 10.1021/acs.joc.1c03127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Here we provide examples that demonstrate the value of using properly designed and easily performed doping experiments to give insights about the nature of the analyte(s) present in a 1H NMR sample. Two mixtures, the first quite complex and the second far less so, have been chosen: (i) the crude pyrolysate from reaction of butyric acid in (supercritical) water at 600 °C and (ii) a mixture of two basic amines. In the former, 13 distinct carbonyl-containing compounds, ranging in relative concentration of nearly 2 orders of magnitude, were positively identified. The latter highlights the advantage of using a doping experiment as opposed to merely comparing the spectra from two separate samples containing the same analyte.
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Affiliation(s)
- Trinadh Kaicharla
- Department of Chemistry, University of Minnesota, 207 Pleasant Street, SE, Minneapolis, Minnesota 55455, United States
| | - Bhavani Shankar Chinta
- Department of Chemistry, University of Minnesota, 207 Pleasant Street, SE, Minneapolis, Minnesota 55455, United States
| | - Thomas R Hoye
- Department of Chemistry, University of Minnesota, 207 Pleasant Street, SE, Minneapolis, Minnesota 55455, United States
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15
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Abstract
The hexadehydro-Diels-Alder (HDDA) reaction converts a 1,3-diyne bearing a tethered alkyne (the diynophile) into bicyclic benzyne intermediates upon thermal activation. With only a few exceptions, this unimolecular cycloisomerization requires, depending on the nature of the atoms connecting the diyne and diynophile, reaction temperatures of ca. 80-130 °C to achieve a convenient half-life (e.g., 1-10 h) for the reaction. In this report, we divulge a new variant of the HDDA process in which the tether contains a central, quaternized nitrogen atom. This construct significantly lowers the activation barrier for the HDDA cycloisomerization to the benzyne. Moreover, many of the ammonium ion-based, alkyne-containing substrates can be spontaneously assembled, cyclized to benzyne, and trapped in a single-vessel, ambient-temperature operation. DFT calculations provide insights into the origin of the enhanced rate of benzyne formation.
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Affiliation(s)
- Chenlong Zhu
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, Minnesota 55455, United States
| | - Thomas R Hoye
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, Minnesota 55455, United States
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16
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Abstract
We have explored the net-[4 + 2]-cycloadditions of a variety of aryl (or alkenyl) alkynes. Tautomerization via base-catalyzed alkyne-to-allene isomerization produces a transient allene, which undergoes stepwise cyclization with not only a pendant alkyne but also a nitrile. The operative mechanisms for these reactions were studied by density functional theory and compared with the slower thermal cyclization of the precursor alkyne.
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Affiliation(s)
- Niklas Kraemer
- Department of Chemistry, 207 Pleasant St. SE, University of Minnesota, Minneapolis, Minnesota 55455 USA
| | - Rajasekhar Reddy Naredla
- Department of Chemistry, 207 Pleasant St. SE, University of Minnesota, Minneapolis, Minnesota 55455 USA
| | - Thomas R. Hoye
- Department of Chemistry, 207 Pleasant St. SE, University of Minnesota, Minneapolis, Minnesota 55455 USA
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17
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Haque FM, Ishibashi JSA, Lidston CAL, Shao H, Bates FS, Chang AB, Coates GW, Cramer CJ, Dauenhauer PJ, Dichtel WR, Ellison CJ, Gormong EA, Hamachi LS, Hoye TR, Jin M, Kalow JA, Kim HJ, Kumar G, LaSalle CJ, Liffland S, Lipinski BM, Pang Y, Parveen R, Peng X, Popowski Y, Prebihalo EA, Reddi Y, Reineke TM, Sheppard DT, Swartz JL, Tolman WB, Vlaisavljevich B, Wissinger J, Xu S, Hillmyer MA. Defining the Macromolecules of Tomorrow through Synergistic Sustainable Polymer Research. Chem Rev 2022; 122:6322-6373. [PMID: 35133803 DOI: 10.1021/acs.chemrev.1c00173] [Citation(s) in RCA: 37] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Transforming how plastics are made, unmade, and remade through innovative research and diverse partnerships that together foster environmental stewardship is critically important to a sustainable future. Designing, preparing, and implementing polymers derived from renewable resources for a wide range of advanced applications that promote future economic development, energy efficiency, and environmental sustainability are all central to these efforts. In this Chemical Reviews contribution, we take a comprehensive, integrated approach to summarize important and impactful contributions to this broad research arena. The Review highlights signature accomplishments across a broad research portfolio and is organized into four wide-ranging research themes that address the topic in a comprehensive manner: Feedstocks, Polymerization Processes and Techniques, Intended Use, and End of Use. We emphasize those successes that benefitted from collaborative engagements across disciplinary lines.
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Affiliation(s)
- Farihah M Haque
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Jacob S A Ishibashi
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Claire A L Lidston
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1801, United States
| | - Huiling Shao
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Frank S Bates
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Alice B Chang
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Geoffrey W Coates
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1801, United States
| | - Christopher J Cramer
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Paul J Dauenhauer
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - William R Dichtel
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Christopher J Ellison
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Ethan A Gormong
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Leslie S Hamachi
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Thomas R Hoye
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Mengyuan Jin
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Julia A Kalow
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Hee Joong Kim
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Gaurav Kumar
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Christopher J LaSalle
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Stephanie Liffland
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Bryce M Lipinski
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1801, United States
| | - Yutong Pang
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Riffat Parveen
- Department of Chemistry, University of South Dakota, Vermillion, South Dakota 57069, United States
| | - Xiayu Peng
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Yanay Popowski
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri 63130-4899, United States
| | - Emily A Prebihalo
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Yernaidu Reddi
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Theresa M Reineke
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Daylan T Sheppard
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Jeremy L Swartz
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - William B Tolman
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri 63130-4899, United States
| | - Bess Vlaisavljevich
- Department of Chemistry, University of South Dakota, Vermillion, South Dakota 57069, United States
| | - Jane Wissinger
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Shu Xu
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Marc A Hillmyer
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
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18
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Abstract
Tetramethylsilane was recommended for use as an internal reference compound in proton NMR spectroscopy over 60 years ago. However, it is a common practice that researchers reference the analyte chemical shifts to the residual proton resonance in the deuterated solvent in which the spectrum is recorded. Because CDCl3 is the most commonly used NMR solvent for routine analysis of organic compounds, the effect of various functional groups on the CHCl3 resonance is important. Described here are results that show why referencing spectra to TMS rather than CHCl3 in CDCl3 results in more accurate chemical shifts and should be the recommended practice. Simultaneous measurement of separate compartments of unperturbed CDCl3/TMS vis-à-vis CDCl3/TMS/solute solutions using a concentric tube arrangement was key. This study is reported in this venue because the audience/readership is quite appropriate and is, hopefully, both receptive to and appreciative of the guidance provided.
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Affiliation(s)
- Alexander L Guzman
- Department of Chemistry, 207 Pleasant Street SE, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Thomas R Hoye
- Department of Chemistry, 207 Pleasant Street SE, University of Minnesota, Minneapolis, Minnesota 55455, United States
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19
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Chinta BS, Arora S, Hoye TR. Trapping Reactions of Benzynes Initiated by Intramolecular Nucleophilic Addition of a Carbonyl Oxygen to the Electrophilic Aryne. Org Lett 2022; 24:425-429. [PMID: 34958573 PMCID: PMC8848297 DOI: 10.1021/acs.orglett.1c04110] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
We describe here reactions in which a carbonyl oxygen atom initiates cascade reactions by nucleophilic attack on a covalently attached benzyne. The benzynes are produced by thermal cyclization of triynes via hexadehydro-Diels-Alder reaction. The initially produced oxocarbenium/aryl carbanionic zwitterion is protonated in situ by an external protic nucleophile (NuH) of appropriate acidity. The resulting ion pair (oxocarbenium+/Nu-) collapses through several different mechanistic manifolds, adding to the diversity of structural classes that can be generated.
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Affiliation(s)
- Bhavani Shankar Chinta
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, MN 55455
| | - Sahil Arora
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, MN 55455
| | - Thomas R. Hoye
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, MN 55455.,Corresponding Author:
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20
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Lynn M, Pierson Smela M, Hoye TR. Silicon as a powerful control element in HDDA chemistry: redirection of innate cyclization preferences, functionalizable tethers, and formal bimolecular HDDA reactions. Chem Sci 2021; 12:13902-13908. [PMID: 34760176 PMCID: PMC8549800 DOI: 10.1039/d1sc04082k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Accepted: 09/22/2021] [Indexed: 11/21/2022] Open
Abstract
The 1,3-diyne and diynophile in hexadehydro-Diels–Alder (HDDA) reaction substrates are typically tethered by linker units that consist of C, O, N, and/or S atoms. We describe here a new class of polyynes based on silicon-containing tethers that can be disposed of and/or functionalized subsequent to the HDDA reaction. The cyclizations are efficient, and the resulting benzoxasiloles are amenable to protodesilylation, halogenation, oxygenation, and arylation reactions. The presence of the silicon atom can also override the innate mode of cyclization in some cases, an outcome attributable to a β-silyl effect on the structure of intermediate diradicals. Overall, this strategy equates formally to an otherwise unknown, bimolecular HDDA reaction and expands the versatility of this body of aryne chemistry. A designer silicon-containing linker enables HDDA chemistry that complements known modes of reactivity. Subsequent removal of the Si liberates a benzenoid product that is formally the result of an intermolecular HDDA reaction.![]()
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Affiliation(s)
- Mandy Lynn
- Department of Chemistry, University of Minnesota 207 Pleasant St. SE Minneapolis MN 55455 USA
| | - Merrick Pierson Smela
- Department of Chemistry, University of Minnesota 207 Pleasant St. SE Minneapolis MN 55455 USA
| | - Thomas R Hoye
- Department of Chemistry, University of Minnesota 207 Pleasant St. SE Minneapolis MN 55455 USA
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21
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Zhu C, Zhang J, Hoye TR. De novo Assembly of the Benzenoid Ring as a Core Strategy for Synthesis of the Isoindolinone Natural Products Isohericerin, Erinacerin A, and Sterenin A. Org Lett 2021; 23:7550-7554. [PMID: 34543031 DOI: 10.1021/acs.orglett.1c02752] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Here we describe the use of the hexadehydro-Diels-Alder (HDDA) reaction for the de novo construction of the isoindolinone scaffold and its application to the synthesis of the title natural products. The key isoindolinone-forming HDDA reaction involved an unprecedented substrate motif in which an amide carbonyl group was conjugated to the 4π 1,3-diyne component. In addition, a dimethylsilyl (-SiMe2H) substituent was exploited to trigger a Fleming-Tamao-Kumada oxidation for the installation of an essential phenolic hydroxyl group.
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Affiliation(s)
- Chenlong Zhu
- Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | - Juntian Zhang
- Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | - Thomas R Hoye
- Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
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22
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Abstract
Here we disclose a sulfurane-mediated method for the formation of dimeric dibenzofuran helicenes via the reaction between diaryl sulfoxides and hexadehydro-Diels-Alder (HDDA) derived benzynes. A variety of S-shaped and U-shaped helicenes were formed under thermal conditions. Both experimental and DFT studies support a sulfur(IV)-based coupling (aka ligand coupling) mechanism involving tetracarbo-ligated S(IV) intermediates undergoing reductive elimination to afford the helicene products. This process involves the de novo generation of five new rings in a single operation and constitutes a new method for the construction of topologically interesting, polycyclic aromatic compounds.
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Affiliation(s)
- Casey B Ritts
- Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | - Thomas R Hoye
- Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
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23
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Abstract
The incorporation of renewable feedstocks into polymer backbones is of great importance in modern polymer science. We report the synthesis of 1,3-diyne polymers derived from the bispropargyl ethers of isosorbide, isomannide, and isoidide. The dialkyne monomers can be polymerized through an adaptation of the Glaser-Hay coupling using a nickel(II) cocatalyst. These well-defined diyne polymers bear an iodoalkyne end group, afforded through an unanticipated reductive elimination pathway, and display glass transition temperatures (Tg) from 55 to 64 °C. Fully saturated, analogous polyethers can be prepared from the hydrogenation of the diyne polymers, and these show Tg values between -10 and -2 °C. Both the 1,3-diyne polymers and the saturated analogues display similar trends in their Tg values vis-à-vis the stereochemical features of the isohexide unit within the backbone. This polymerization provided access to two series of isohexide-based polyethers, the thermal properties of which are influenced by the nature of the 2,4-hexadiynyl and hexamethylene linkers as well as the relative configuration of the bicyclic subunit in the backbone. The reported method represents an important step toward accessing well-defined polyethers from renewable feedstocks using readily available catalysts and convenient ambient conditions.
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Affiliation(s)
- Ethan A. Gormong
- Department of Chemistry, University of Minnesota, 207 Pleasant Street, SE, Minneapolis, Minnesota 55455, United States
| | - Theresa M. Reineke
- Department of Chemistry, University of Minnesota, 207 Pleasant Street, SE, Minneapolis, Minnesota 55455, United States
| | - Thomas R. Hoye
- Department of Chemistry, University of Minnesota, 207 Pleasant Street, SE, Minneapolis, Minnesota 55455, United States
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24
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Wang Q, Hoye TR. Cu(I)-Catalyzed 1,2-Alkynyl-propargylation and -benzylation of Benzyne Derivatives. Org Lett 2021; 23:5448-5451. [PMID: 34180676 DOI: 10.1021/acs.orglett.1c01788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report here a three-component, Cu(I)-catalyzed hexadehydro-Diels-Alder (HDDA) benzyne 1,2-difunctionalization reaction. This protocol allowed the introduction of two different carbon-based substituents onto the in situ-generated benzyne. These substituents were terminal monoynes or diynes partnered with propargylic, benzylic, or allylic chlorides. An example of a sequential HDDA reaction is demonstrated using the product of a 1,3-diyne and a propargylic halide, itself a newly created HDDA precursor.
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Affiliation(s)
- Qile Wang
- Department of Chemistry, University of Minnesota, 207 Pleasant Street Southeast, Minneapolis, Minnesota 55455, United States
| | - Thomas R Hoye
- Department of Chemistry, University of Minnesota, 207 Pleasant Street Southeast, Minneapolis, Minnesota 55455, United States
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25
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Abstract
We report here elaboration of a cascade strategy for naphthyne formation using Kobayashi benzynes as diynophiles in a subsequent in situ hexadehydro-Diels-Alder reaction. Density functional theory computations suggest that the strained benzynes act as "super-diynophiles" in this transformation. The reaction requires only mildly basic and ambient temperature conditions and allows for rapid construction of various naphthalenic products. The trapping efficiencies of several arynophiles were determined using the benzyne to naphthyne cyclization as an internal clock reaction.
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Affiliation(s)
- Sahil Arora
- Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | - Thomas R Hoye
- Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
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26
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Abstract
Arylhydrazines (ArNαHNβH2) are ambident nucleophiles. We describe here their reactivity with benzynes generated in situ by thermal cyclization of several multiynes. Products arising from attack of both the alpha- and beta-nitrogen atoms are observed. These competitive modes of reaction were explored by DFT calculations. Substituent effects on the site-selectivity for several substituted phenylhydrazines were explored. Interestingly, the hydrazo products from beta-attack (ArNHNHAr') can be oxidized, sometimes in situ by oxygen alone, to give structurally complex, unsymmetrical azoarenes (ArN═NAr'). Toluenesulfonohydrazide and benzohydrazide analogues were each demonstrated to undergo similar transformations, including oxidation to the corresponding benzyne-trapped azo compounds.
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Affiliation(s)
- Dorian S Sneddon
- Department of Chemistry, University of Minnesota, 207 Pleasant Street, Southeast, Minneapolis, Minnesota 55455 United States
| | - Thomas R Hoye
- Department of Chemistry, University of Minnesota, 207 Pleasant Street, Southeast, Minneapolis, Minnesota 55455 United States
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27
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Abstract
Although the parent 2-pyrone is known to react with simple o-benzynes to produce naphthalene derivatives, there appear to be no examples of the successful reaction of coumarin, a benzo-annulated 2-pyrone analogue, with an aryne. We report such a process here using benzynes generated by the hexadehydro-Diels-Alder reaction to produce phenanthrene derivatives (i.e., benzo-annulated naphthalenes). Density functional theory computations were used to help understand the difference in reactivity between 2-pyrone and the slower trapping agent, coumarin. Finally, the reaction of o-benzyne itself [from o-(trimethylsilyl)phenyl triflate and CsF] with coumarin was shown to be viable, although slow.
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Affiliation(s)
- Bhavani Shankar Chinta
- Department of Chemistry, University of Minnesota, 207 Pleasant Street Southeast, Minneapolis, Minnesota 55455, United States
| | - Daniel Lee
- Department of Chemistry, University of Minnesota, 207 Pleasant Street Southeast, Minneapolis, Minnesota 55455, United States
| | - Thomas R Hoye
- Department of Chemistry, University of Minnesota, 207 Pleasant Street Southeast, Minneapolis, Minnesota 55455, United States
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28
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Guptill DM, Chinta BS, Kaicharla T, Xu S, Hoye TR. β-Methyl-δ-valerolactone-containing Thermoplastic Poly(ester-amide)s: Synthesis, Mechanical Properties, and Degradation Behavior. Polym Chem 2021; 12:1310-1316. [PMID: 34354765 PMCID: PMC8330554 DOI: 10.1039/d1py00040c] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Poly(ester-amide)s (PEAs) have been prepared from (glucose-derived) β-methyl-δ-valerolactone (MVL) by reaction of MVL-derived diamidodiols with diacid chlorides in solution to form poly(ester-amide)s having alternating diester-diamide subunits. The PEAs formed by this method exhibit plastic properties and are of sufficiently high molecular weight to be tough, ductile materials (stress at break: 41-53 MPa, strain at break: 530-640%). The length of the methylene linker unit (n = 1,2,3) between amide groups of the diamidodiols affects the Young's modulus; longer linkers reduce the stiffness of the materials. This allows tuning of the properties by judicious choice of precursors. MVL was also converted to a diacid chloride that was then used to prepare a PEA that is 76 wt% MVL-derived. The degradation rates of suspensions of these new PEAs in basic aqueous media were benchmarked and their instability in aqueous acid was also observed. NMR studies were used to detect the hydrolytic degradation products of both these PEAs as well as a structurally simpler analog.
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Affiliation(s)
- David M Guptill
- Department of Chemistry University of Minnesota, 207 Pleasant St. SE, Minneapolis, Minnesota 55455 USA
| | - Bhavani Shankar Chinta
- Department of Chemistry University of Minnesota, 207 Pleasant St. SE, Minneapolis, Minnesota 55455 USA
| | - Trinadh Kaicharla
- Department of Chemistry University of Minnesota, 207 Pleasant St. SE, Minneapolis, Minnesota 55455 USA
| | - Shu Xu
- Department of Chemistry University of Minnesota, 207 Pleasant St. SE, Minneapolis, Minnesota 55455 USA
| | - Thomas R Hoye
- Department of Chemistry University of Minnesota, 207 Pleasant St. SE, Minneapolis, Minnesota 55455 USA
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29
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Abstract
The hexadehydro-Diels-Alder (HDDA) reaction is the thermal cyclization of an alkyne and a 1,3-diyne to generate a benzyne intermediate. This is then rapidly trapped, in situ, by a variety of species to yield highly functionalized benzenoid products. In contrast to nearly all other methods of aryne generation, no other reagents are required to produce an HDDA benzyne. The versatile and customizable nature of the process has attracted much attention due not only to its synthetic potential but also because of the fundamental mechanistic insights the studies often afford. The authors have attempted to provide here a comprehensive compilation of publications appearing by mid-2020 that describe experimental results of HDDA reactions.
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Affiliation(s)
- Lucas L Fluegel
- Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | - Thomas R Hoye
- Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
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30
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Lopes DT, Hoye TR, Alvarenga ES. Characterization of stereoisomeric 5-(2-nitro-1-phenylethyl)furan-2(5H)-ones by computation of 1 H and 13 C NMR chemical shifts and electronic circular dichroism spectra. Magn Reson Chem 2021; 59:43-51. [PMID: 32621355 PMCID: PMC7985851 DOI: 10.1002/mrc.5073] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 06/28/2020] [Accepted: 06/29/2020] [Indexed: 06/11/2023]
Abstract
In the present work, we describe the preparation of two diastereomers from the enantioselective Michael addition of furan-2(5H)-one to (E)-(2-nitrovinyl)benzene catalyzed by a dinuclear Zn-complex. The relative configurations of the diastereomeric products were assigned by comparing nuclear magnetic resonance (NMR) experimental chemical shift data with those computed by density functional theory (DFT) methods. Corrected mean absolute error (CMAE) and CP3 analyses were used to compare the data sets. The absolute configuration of each diastereomer was initially assigned by analysis of electronic circular dichroism (ECD) data, which was consistent with that of the known X-ray crystallographic structure of the product of a related reaction, namely, (R)-5-((R)-1-(4-chlorophenyl)-2-nitroethyl)furan-2(5H)-one.
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Affiliation(s)
- Dayane T. Lopes
- Department of Chemistry, Universidade Federal de Viçosa, Viçosa, MG 36571-900, Brazil
| | - Thomas R. Hoye
- Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, USA
| | - Elson S. Alvarenga
- Department of Chemistry, Universidade Federal de Viçosa, Viçosa, MG 36571-900, Brazil
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31
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Guptill DM, Chinta BS, Kaicharla T, Xu S, Hoye TR. Correction: β-Methyl-δ-valerolactone-containing thermoplastic poly(ester-amide)s: synthesis, mechanical properties, and degradation behavior. Polym Chem 2021. [DOI: 10.1039/d1py90069b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Correction for ‘β-Methyl-δ-valerolactone-containing thermoplastic poly(ester-amide)s: synthesis, mechanical properties, and degradation behavior’ by David M. Guptill et al., Polym. Chem., 2021, 12, 1310–1316, DOI: 10.1039/D1PY00040C.
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Affiliation(s)
| | | | | | - Shu Xu
- Department of Chemistry University of Minnesota
- Minneapolis
- USA
| | - Thomas R. Hoye
- Department of Chemistry University of Minnesota
- Minneapolis
- USA
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32
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Willoughby PH, Jansma MJ, Hoye TR. Addendum: A guide to small-molecule structure assignment through computation of (¹H and ¹³C) NMR chemical shifts. Nat Protoc 2020; 15:2277. [PMID: 31949288 DOI: 10.1038/s41596-020-0293-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
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Affiliation(s)
| | - Matthew J Jansma
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota, USA
| | - Thomas R Hoye
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota, USA.
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33
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Abstract
We report here the synthesis of poly(4-ketovalerolactone) (PKVL) via ring-opening transesterification polymerization (ROTEP) of the monomer 4-ketovalerolactone (KVL, two steps from levulinic acid). The polymerization of KVL proceeds to high equilibrium monomer conversion (up to 96% in the melt) to give the semicrystalline polyketoester PKVL with low dispersity. PKVL displays glass transition temperatures of 7 °C and two melting temperatures at 132 and 148 °C. This polyester can be chemically recycled through hydrolytic degradation. Under aqueous neutral or acidic conditions, the dominating pathway for polyester hydrolysis is through backbiting from the chain end. Under basic conditions, mid-chain cleavage, accelerated by the ketone carbonyl group in the backbone, promotes the hydrolysis of nearby backbone ester bonds. The final hydrolysis product is 5-hydroxylevulinic acid, the ring opened hydrolysis product of KVL. PKVL was also observed to degrade under the action of a Brønsted acid to a bis-spirocyclic dilactone natural product altaicadispirolactone, which is a dimer of KVL. This constitutes a rare example of a one-step synthesis of a secondary metabolite of non-trivial structure in which a polymer was the starting material and the sole source of matter. Analogous ROTEP of the isomeric 4-membered lactone 4-acetyl-β-propiolactone (APL) was also explored, although this chemistry was not as well-behaved as the KVL to PKVL polymerization.
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Affiliation(s)
- Shu Xu
- Department of Chemistry, 207 Pleasant Street, SE, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Yuanxian Wang
- Department of Chemistry, 207 Pleasant Street, SE, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Thomas R Hoye
- Department of Chemistry, 207 Pleasant Street, SE, University of Minnesota, Minneapolis, Minnesota 55455, United States
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34
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Abstract
o-Benzynes can be utilized to construct heterocyclic motifs using various nucleophilic and cycloaddition trapping reactions. Acridines have been synthesized by capture of C,N-diarylimines with benzynes generated by classical methods (i.e., from ortho-elimination of precursor arene compounds), although in poor yields. We report here that these imines can be trapped by benzynes generated by the hexadehydro-Diels-Alder (HDDA) reaction in an efficient manner to produce 1,4-dihydroacridine products. These dihydroacridines were subsequently aromatized using MnO2 to provide structurally complex acridines.
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Affiliation(s)
- Sahil Arora
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, MN 55455 USA
| | - Dorian S Sneddon
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, MN 55455 USA
| | - Thomas R Hoye
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, MN 55455 USA
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35
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Abstract
Eight 4-carboalkoxyvalerolactones (CRVLs), varying in the composition of their alkyl (R) side chains, were synthesized from malic acid and subjected to ring-opening transesterification polymerization (ROTEP) using diphenyl phosphate [DPP, (PhO)2PO2H] as a catalyst. Each CRVL produced a semicrystalline poly(4-carboalkoxyvalerolactone) (PCRVL), and the nature of the R group impacted the thermal transitions of these polyesters. Bulk polymerizations at 70 °C allowed for preparation of high molar mass samples that contained small amounts of branching, as evidenced by 1H NMR spectroscopy, MALDI spectrometry, size-exclusion chromatography, and eliminative degradation. Tensile testing of these lightly branched, high molar mass samples revealed that these polyesters are tough (tensile toughness values up to 88 ± 33 MJ•m-3) and have Young's moduli (E) up to 186 ± 13 MPa. The acid- and base-catalyzed hydrolytic degradation of the PCRVLs was quantitatively monitored using total organic carbon analysis, and effect of the alkyl chain length on PCRVL hydrolysis rate was determined. Finally, the methyl ester variant of these malic acid-derived thermoplastics is known to be chemically recyclable.
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Affiliation(s)
- Grant W. Fahnhorst
- Department of Chemistry, 207 Pleasant Street, SE, University of Minnesota, Minneapolis, MN 55455
| | - Guilhem X. De Hoe
- Department of Chemistry, 207 Pleasant Street, SE, University of Minnesota, Minneapolis, MN 55455
| | - Marc A. Hillmyer
- Department of Chemistry, 207 Pleasant Street, SE, University of Minnesota, Minneapolis, MN 55455
| | - Thomas R. Hoye
- Department of Chemistry, 207 Pleasant Street, SE, University of Minnesota, Minneapolis, MN 55455
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36
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Abstract
The generation of pyridynes from diyne nitriles is reported. These cyano-containing precursors are analogues of the triyne substrates typically used for the hexadehydro-Diels-Alder (HDDA) cycloisomerization reactions that produce ring-fused benzynes. Hence, the new processes described represent aza-HDDA reactions. Depending on the location of the nitrile, either 3,4-pyridynes (from 1,3-diynes containing a tethered cyano group) or 2,3-pyridynes (from 1-cyanoethyne derivatives containing a tethered alkyne) are produced. In situ trapping of these reactive intermediates leads to highly substituted and functionalized pyridine derivatives. In several instances, unprecedented pyridyne trapping reactions are seen. Differences in reaction energetics between the aza-HDDA substrates and that of their analogous HDDA (triyne) substrates are discussed.
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Affiliation(s)
- Severin K Thompson
- Department of Chemistry , University of Minnesota , 207 Pleasant Street SE , Minneapolis , Minnesota 55455 , United States
| | - Thomas R Hoye
- Department of Chemistry , University of Minnesota , 207 Pleasant Street SE , Minneapolis , Minnesota 55455 , United States
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37
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Arora S, Zhang J, Pogula V, Hoye TR. Reactions of thermally generated benzynes with six-membered N-heteroaromatics: pathway and product diversity. Chem Sci 2019; 10:9069-9076. [PMID: 31827748 PMCID: PMC6889833 DOI: 10.1039/c9sc03479j] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2019] [Accepted: 08/13/2019] [Indexed: 12/31/2022] Open
Abstract
We report here various pathways by which six-membered N-heteroaromatic compounds react with benzynes that are generated by the HDDA reaction. The initially formed 1,3-zwitterionic species (a) can collapse intramolecularly to give novel 1 : 1 adducts of the heterocycle and benzyne; (b) can react with an externally added, electrophilic third-component to give functionalized heterocyclic products; or (c) can react with an external protic nucleophile to produce, following collapse of the ion pair resulting from protonation of the zwitterion, a variety of three-component assemblies. Mechanisms for formation of some of the 1 : 1 adducts are supported by DFT methods. The scope of the protic nucleophilic coupling was also expanded to a two-pot operation by using triflic acid as a protic "non-nucleophile", followed by the addition of a suitably reactive nucleophile.
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Affiliation(s)
- Sahil Arora
- Department of Chemistry
, University of Minnesota
,
207 Pleasant St., SE
, Minneapolis
, MN 55455
, USA
.
| | - Juntian Zhang
- Department of Chemistry
, University of Minnesota
,
207 Pleasant St., SE
, Minneapolis
, MN 55455
, USA
.
| | - Vedamayee Pogula
- Department of Chemistry
, University of Minnesota
,
207 Pleasant St., SE
, Minneapolis
, MN 55455
, USA
.
| | - Thomas R. Hoye
- Department of Chemistry
, University of Minnesota
,
207 Pleasant St., SE
, Minneapolis
, MN 55455
, USA
.
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38
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Abstract
Here we disclose a cascade strategy for naphthyne formation that capitalizes on the traditional benzyne generation (i.e., from an ortho-silyl aryl triflate) and the thermal hexadehydro-Diels-Alder (HDDA) reaction. In this transformation, three distinct aryne species work in tandem, two of which can be formally considered as a 1,2-benzidyne, and each undergoes a different type of trapping event. Many examples were explored by varying the naphthyne capture chemistry as well as the 1,2-benzdiyne equivalent. This strategy enables rapid construction of various naphthalene products and has potential for the synthesis of extended polycyclic arenes.
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Affiliation(s)
- Xiao Xiao
- Department of Chemistry , University of Minnesota , 207 Pleasant Street SE , Minneapolis , Minnesota 55455 , United States
| | - Thomas R Hoye
- Department of Chemistry , University of Minnesota , 207 Pleasant Street SE , Minneapolis , Minnesota 55455 , United States
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39
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Zhang J, Hoye TR. Divergent Reactivity during the Trapping of Benzynes by Glycidol Analogs: Ring Cleavage via Pinacol-Like Rearrangements vs Oxirane Fragmentations. Org Lett 2019; 21:2615-2619. [PMID: 30969776 DOI: 10.1021/acs.orglett.9b00595] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Hydroxy-containing cyclic ethers react with thermally generated benzynes to produce aryl ethers. Diverse reactivity was observed. Cleavage of the cyclic ether was involved in most of the pathways. The transformations are rationalized via initial formation of oxonium ion-containing 1,3-zwitterions arising from preferential nucleophilic attack on the benzyne by the ether oxygen. Pinacol-like rearrangements, including ring expansion, to yield aldehydes or ketones and oxirane fragmentations to generate aryl enol ethers were main competing events.
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Affiliation(s)
- Juntian Zhang
- Department of Chemistry , University of Minnesota , 207 Pleasant Street SE , Minneapolis , Minnesota 55455 , United States
| | - Thomas R Hoye
- Department of Chemistry , University of Minnesota , 207 Pleasant Street SE , Minneapolis , Minnesota 55455 , United States
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40
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Abstract
A new thermal isomerization of polyynes is described. Benzyne intermediates substituted by a C(RR')OR'' substituent adjacent to one of the benzyne sp-hybridized carbons give rise to products in which the OR' moiety has migrated to the proximal benzyne carbon. This process likely proceeds via sequential formation of multiple reactive intermediates: an initial thermally generated benzyne, a strained benzoxetenonium ion, and an o-quinone methide. As some examples demonstrate, the overall transformation can be quite efficient. The mechanism of this novel reaction is further supported by experiments and DFT calculations.
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Affiliation(s)
- Hang Shen
- Department of Chemistry , University of Minnesota , 207 Pleasant Street SE , Minneapolis , Minnesota 55455 , United States
| | - Xiao Xiao
- Department of Chemistry , University of Minnesota , 207 Pleasant Street SE , Minneapolis , Minnesota 55455 , United States
| | - Thomas R Hoye
- Department of Chemistry , University of Minnesota , 207 Pleasant Street SE , Minneapolis , Minnesota 55455 , United States
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41
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Neitzel AE, Barreda L, Trotta JT, Fahnhorst GW, Haversang TJ, Hoye TR, Fors BP, Hillmyer MA. Hydrolytically-degradable homo- and copolymers of a strained exocyclic hemiacetal ester. Polym Chem 2019. [DOI: 10.1039/c9py00797k] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report the cationic ring-opening homo- and copolymerization of the 7-membered exocyclic hemiacetal ester 7-methoxyoxepan-2-one (MOPO) to afford poly(7-methoxyoxepan-2-one) [poly(MOPO)] and its copolymers with isobutyl vinyl ether (IBVE).
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Affiliation(s)
- Angelika E. Neitzel
- Department of Chemical Engineering and Materials Science
- University of Minnesota
- Minneapolis
- USA
| | - Leonel Barreda
- Department of Chemistry
- University of Minnesota
- Minneapolis
- USA
| | - Jacob T. Trotta
- Department of Chemistry and Chemical Biology
- Cornell University
- Ithaca
- USA
| | | | - Thomas J. Haversang
- Department of Chemical Engineering and Materials Science
- University of Minnesota
- Minneapolis
- USA
| | - Thomas R. Hoye
- Department of Chemistry
- University of Minnesota
- Minneapolis
- USA
| | - Brett P. Fors
- Department of Chemistry and Chemical Biology
- Cornell University
- Ithaca
- USA
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42
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Abstract
Reactions of thermally generated benzynes with diaziridines are reported. These trapping reactions follow the same pathway as reported earlier by Heine and co-workers with electron-deficient alkynes. The resulting N-arylhydrazones were obtained efficiently in a single step. The preference for the mode of addition of the nucleophilic diaziridine nitrogen atom to the more electrophilic benzyne carbon was consistent with what is predicted on the basis of distortion analysis. The feasibility of converting the hydrazone into a Fisher-indole adduct was demonstrated.
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Affiliation(s)
- Sahil Arora
- Department of Chemistry , University of Minnesota , 207 Pleasant Street SE , Minneapolis , Minnesota 55455 , United States
| | - Vignesh Palani
- Department of Chemistry , University of Minnesota , 207 Pleasant Street SE , Minneapolis , Minnesota 55455 , United States
| | - Thomas R Hoye
- Department of Chemistry , University of Minnesota , 207 Pleasant Street SE , Minneapolis , Minnesota 55455 , United States
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43
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Xiao X, Wang T, Xu F, Hoye TR. Cu I -Mediated Bromoalkynylation and Hydroalkynylation Reactions of Unsymmetrical Benzynes: Complementary Modes of Addition. Angew Chem Int Ed Engl 2018; 57:16564-16568. [PMID: 30390400 DOI: 10.1002/anie.201811783] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2018] [Indexed: 11/10/2022]
Abstract
Benzynes formed by heating a suitable triyne (or tetrayne) substrate are shown to react with in situ generated alkynyl copper species. The latter are compatible with the polyyne substrates and two types of chemistries have been achieved: (i) 1-bromo-1-alkynes efficiently undergo net bromoalkynylation of the (unsymmetrical) benzynes and (ii) in situ generated alkynylcopper species give rise to hydroalkynylation products. The regiochemical preferences of these two modes of reaction are complementary to one another with respect to the position of alkynyl substituent in the final products.
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Affiliation(s)
- Xiao Xiao
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, MN, 55455, USA
| | - Tao Wang
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, MN, 55455, USA
| | - Feng Xu
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, MN, 55455, USA
| | - Thomas R Hoye
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, MN, 55455, USA
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44
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Abstract
Reactions of tethered, tertiary sulfonamides with thermally generated benzynes are reported. Typically, the N-S bonds in the substrates cleave, and saturated heterocycles [tetrahydroquinolines ( n = 2) and indolines ( n = 1)] are formed. The process is accompanied by either sulfonyl transfer or desulfonylation from a zwitterionic intermediate, with the favored pathway being largely dependent upon the size (5- vs 6-membered) of the N-containing ring in the zwitterion.
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Affiliation(s)
- Yuanxian Wang
- Department of Chemistry, 207 Pleasant St. SE, University of Minnesota, Minneapolis, MN 55455
| | | | - Thomas R. Hoye
- Department of Chemistry, 207 Pleasant St. SE, University of Minnesota, Minneapolis, MN 55455
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45
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Xiao X, Wang T, Xu F, Hoye TR. CuI
-Mediated Bromoalkynylation and Hydroalkynylation Reactions of Unsymmetrical Benzynes: Complementary Modes of Addition. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201811783] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Xiao Xiao
- Department of Chemistry; University of Minnesota; 207 Pleasant St. SE Minneapolis MN 55455 USA
| | - Tao Wang
- Department of Chemistry; University of Minnesota; 207 Pleasant St. SE Minneapolis MN 55455 USA
| | - Feng Xu
- Department of Chemistry; University of Minnesota; 207 Pleasant St. SE Minneapolis MN 55455 USA
| | - Thomas R. Hoye
- Department of Chemistry; University of Minnesota; 207 Pleasant St. SE Minneapolis MN 55455 USA
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46
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Abstract
Boron trifluoride is observed to promote a variety of C-H insertion reactions of benzynes bearing pendant alkyl groups. Computations and various mechanistic studies indicate that BF3 engages the strained π-bond to confer carbene-like character on the adjacent, noncoordinated benzyne carbon. This represents an unprecedented catalytic role for a non-transition metal such as BF3.
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Affiliation(s)
- Hang Shen
- Department of Chemistry , University of Minnesota , 207 Pleasant Street , SE Minneapolis , Minnesota 55455 , United States
| | - Xiao Xiao
- Department of Chemistry , University of Minnesota , 207 Pleasant Street , SE Minneapolis , Minnesota 55455 , United States
| | - Moriana K Haj
- Department of Chemistry , University of Minnesota , 207 Pleasant Street , SE Minneapolis , Minnesota 55455 , United States
| | - Patrick H Willoughby
- Department of Chemistry , University of Minnesota , 207 Pleasant Street , SE Minneapolis , Minnesota 55455 , United States
| | - Thomas R Hoye
- Department of Chemistry , University of Minnesota , 207 Pleasant Street , SE Minneapolis , Minnesota 55455 , United States
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47
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Fahnhorst GW, Stasiw DE, Tolman WB, Hoye TR. Isomerization of Linear to Hyperbranched Polymers: Two Isomeric Lactones Converge via Metastable Isostructural Polyesters to a Highly Branched Analogue. ACS Macro Lett 2018; 7:1144-1148. [PMID: 35651265 DOI: 10.1021/acsmacrolett.8b00621] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report here the Zn(II)-catalyzed convergence of two metastable and isostructural polyesters to an isomeric polymer having a hyperbranched architecture. Ring-opening transesterification polymerization (ROTEP) of 4-carbomethoxyvalerolactone (CMVL) under Brønsted catalysis is known to give the linear polyester PCMVL. We show here that this can be isomerized to the equilibrated (and highly branched) polyester EQ-PCMVL. Analysis of the fragments obtained from eliminative degradation of EQ-PCMVL were critical in the formulation of its structure. The isomerization of PCMVL to EQ-PCMVL is a direct consequence of the presence of the second ester functional group in the CMVL ester-lactone, a rarely studied class of monomer. Zn(II)-catalysis of the ROTEP of the isomeric β-lactone, 2-(2-carbomethoxyethyl)propiolactone (isoCMVL), as well as isomerization of the isostructural linear homopolymer derived from that isomeric monomer, led to the same EQ-PCMVL. These results suggest a new strategy for the introduction of branching into various polyesters.
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Affiliation(s)
- Grant W. Fahnhorst
- Department of Chemistry, University of Minnesota, 207 Pleasant St., SE, Minneapolis, Minnesota 55455, United States
| | - Daniel E. Stasiw
- Department of Chemistry, University of Minnesota, 207 Pleasant St., SE, Minneapolis, Minnesota 55455, United States
| | - William B. Tolman
- Department of Chemistry, University of Minnesota, 207 Pleasant St., SE, Minneapolis, Minnesota 55455, United States
| | - Thomas R. Hoye
- Department of Chemistry, University of Minnesota, 207 Pleasant St., SE, Minneapolis, Minnesota 55455, United States
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48
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Zhang J, Page ACS, Palani V, Chen J, Hoye TR. Atypical Mode of [3 + 2]-Cycloaddition: Pseudo-1,3-dipole Behavior in Reactions of Electron-Deficient Thioamides with Benzynes. Org Lett 2018; 20:5550-5553. [PMID: 30156418 DOI: 10.1021/acs.orglett.8b02133] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Thioamides bearing electron-withdrawing groups on the thiocarbonyl carbon atom react with benzynes [generated by the hexadehydro-Diels-Alder cycloisomerization] in an unprecedented fashion. Namely, the dihydrobenzothiazole products are consistent with a pathway involving initial formation of a stabilized ammonium ylide by a rare type of [3 + 2]-cycloaddition reaction. The fate of this species depends upon the nature of the R group(s) attached to the ylide nitrogen atom. The demonstration of new modes of reactivity represents the major advance arising from this study.
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Affiliation(s)
- Juntian Zhang
- Department of Chemistry , University of Minnesota , 207 Pleasant Street SE , Minneapolis , Minnesota 55455 , United States
| | - Annika C S Page
- Department of Chemistry , University of Minnesota , 207 Pleasant Street SE , Minneapolis , Minnesota 55455 , United States
| | - Vignesh Palani
- Department of Chemistry , University of Minnesota , 207 Pleasant Street SE , Minneapolis , Minnesota 55455 , United States
| | - Junhua Chen
- Department of Chemistry , University of Minnesota , 207 Pleasant Street SE , Minneapolis , Minnesota 55455 , United States
| | - Thomas R Hoye
- Department of Chemistry , University of Minnesota , 207 Pleasant Street SE , Minneapolis , Minnesota 55455 , United States
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49
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Abstract
A synthetic strategy formally equivalent to an intermolecular hexadehydro-Diels-Alder (HDDA) reaction is described. Sulfur-based linkers were designed and constructed by joining terminal alkynes or diynes using alkyne thiolate chemistry. The resulting tetraynes and triynes successfully underwent HDDA cyclization and benzyne trapping. Linker removal by reductive desulfurization was uneventful. The strategy was also found suitable for the tetradehydro-Diels-Alder (TDDA) reaction.
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Affiliation(s)
- Merrick Pierson Smela
- Department of Chemistry , University of Minnesota , 207 Pleasant Street SE , Minneapolis , Minnesota 55455 , United States
| | - Thomas R Hoye
- Department of Chemistry , University of Minnesota , 207 Pleasant Street SE , Minneapolis , Minnesota 55455 , United States
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50
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Abstract
Thermal isomerizations of various propargyl 3-acylpropiolates are described. Many result in the formation of 3-acylbutenolides. These reactions appear to proceed through intermediate 2,3-dehydropyrans (strained cyclic allenes), which then isomerize in a previously unobserved fashion. Competitive processes that provide additional mechanistic insights are also described.
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Affiliation(s)
- Yuanxian Wang
- Department of Chemistry , University of Minnesota , 207 Pleasant St. SE , Minneapolis , Minnesota 55455 , United States
| | - Thomas R Hoye
- Department of Chemistry , University of Minnesota , 207 Pleasant St. SE , Minneapolis , Minnesota 55455 , United States
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