1
|
Yang S, Hu H, Chen M. Photoinduced Palladium-Catalyzed Regio- and Chemoselective Elimination of Primary Alkyl Bromides: A Mild Route to Synthesize Unactivated Terminal Olefins. Org Lett 2023; 25:7968-7973. [PMID: 37888796 DOI: 10.1021/acs.orglett.3c02980] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2023]
Abstract
Presented is a highly efficient method for visible-light-induced regio- and chemoselective elimination of alkyl halides yielding unactivated terminal olefins vital in organic synthesis. Achieved through ligand control, the reaction exhibits remarkable regioselectivity and suppresses undesired side reactions, particularly 1,5-hydrogen atom transfer (HAT). The process favors primary alkyl halides while preserving secondary and tertiary alkyl bromides, thereby enabling the incorporation of terminal olefins in complex molecules for late-stage functionalization.
Collapse
Affiliation(s)
- Sen Yang
- Jiangsu Key Laboratory of Advanced Catalytic Materials & Technology, School of Petrochemical Engineering, Changzhou University, Changzhou 213164, China
| | - Hao Hu
- Jiangsu Key Laboratory of Advanced Catalytic Materials & Technology, School of Petrochemical Engineering, Changzhou University, Changzhou 213164, China
| | - Ming Chen
- Jiangsu Key Laboratory of Advanced Catalytic Materials & Technology, School of Petrochemical Engineering, Changzhou University, Changzhou 213164, China
| |
Collapse
|
2
|
Zhao H, McMillan AJ, Constantin T, Mykura RC, Juliá F, Leonori D. Merging Halogen-Atom Transfer (XAT) and Cobalt Catalysis to Override E2-Selectivity in the Elimination of Alkyl Halides: A Mild Route toward contra-Thermodynamic Olefins. J Am Chem Soc 2021; 143:14806-14813. [PMID: 34468137 DOI: 10.1021/jacs.1c06768] [Citation(s) in RCA: 52] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
We report here a mechanistically distinct tactic to carry E2-type eliminations on alkyl halides. This strategy exploits the interplay of α-aminoalkyl radical-mediated halogen-atom transfer (XAT) with desaturative cobalt catalysis. The methodology is high-yielding, tolerates many functionalities, and was used to access industrially relevant materials. In contrast to thermal E2 eliminations where unsymmetrical substrates give regioisomeric mixtures, this approach enables, by fine-tuning of the electronic and steric properties of the cobalt catalyst, to obtain high olefin positional selectivity. This unprecedented mechanistic feature has allowed access to contra-thermodynamic olefins, elusive by E2 eliminations.
Collapse
Affiliation(s)
- Huaibo Zhao
- Department of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - Alastair J McMillan
- Department of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - Timothée Constantin
- Department of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - Rory C Mykura
- Department of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - Fabio Juliá
- Department of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - Daniele Leonori
- Department of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| |
Collapse
|
3
|
Ma Y, Algera RF, Woltornist RA, Collum DB. Sodium Diisopropylamide-Mediated Dehydrohalogenations: Influence of Primary- and Secondary-Shell Solvation. J Org Chem 2019; 84:10860-10869. [PMID: 31436099 PMCID: PMC6737842 DOI: 10.1021/acs.joc.9b01428] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
![]()
Eliminations of alkyl
halides by sodium diisopropylamide (NaDA)
in tetrahydrofuran (THF)/hexane or THF/N,N-dimethylethylamine
(DMEA) solutions are facile
and complementary to analogous reactions of lithium diisopropylamide
in THF. Rate studies show a dominance of monomer-based metalations
and prevalent secondary-shell solvation effects overlaid on primary-shell
effects. 1-Halooctanes exclusively undergo elimination rather than
substitution. Rate and isotopic labeling studies on 1-bromooctane
reveal an E2-like elimination pathway via trisolvated NaDA monomer.
By contrast, 1-chlorooctane is eliminated via disolvated monomer through
a carbenoid mechanism. exo-2-Norbornyl chloride and
bromide are also eliminated via disolvated monomer; a syn E2 mechanism
is inferred for these substrates. The cis- and trans-4-tert-butylcyclohexyl bromides show
a preference for the elimination of the cis isomer (kcis/ax/ktrans/eq = 10). Rate
and isotopic labeling studies are consistent with a trans-diaxial
E2 elimination via trisolvated monomer for the cis isomer and a carbenoid
mechanism via disolvated monomer for the trans isomer. Vicinal haloethers
show substrate-dependent reactivities, affording alkynes and enol
ethers. trans-1-Bromo-2-methoxycyclohexane provides
enol ether 1-methoxycyclohexene, while trans-1-bromo-2-methoxycyclooctane
provides dimeric products consistent with fleeting cycloocta-1,2-diene
(cyclic allene), which was fully characterized as two conformers.
Collapse
Affiliation(s)
- Yun Ma
- Department of Chemistry and Chemical Biology, Baker Laboratory , Cornell University , Ithaca , New York 14853-1301 , United States
| | - Russell F Algera
- Department of Chemistry and Chemical Biology, Baker Laboratory , Cornell University , Ithaca , New York 14853-1301 , United States
| | - Ryan A Woltornist
- Department of Chemistry and Chemical Biology, Baker Laboratory , Cornell University , Ithaca , New York 14853-1301 , United States
| | - David B Collum
- Department of Chemistry and Chemical Biology, Baker Laboratory , Cornell University , Ithaca , New York 14853-1301 , United States
| |
Collapse
|
4
|
Mack KA, Collum DB. Case for Lithium Tetramethylpiperidide-Mediated Ortholithiations: Reactivity and Mechanisms. J Am Chem Soc 2018; 140:4877-4883. [PMID: 29589920 PMCID: PMC6141241 DOI: 10.1021/jacs.8b00590] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Rate and mechanistic studies of ortholithiations by lithium 2,2,6,6-tetramethylpiperidide focus on four arenes: 1,4-bis(trifluoromethyl)benzene, 1,3-bis(trifluoromethyl)benzene, 1,3-dimethoxybenzene, and 4,4-dimethyl-2-phenyl-2-oxazoline. Metalations occur via substrate-dependent combinations of monosolvated monomer, disolvated monomer, and tetrasolvated dimer (triple ions). Density functional theory computational studies augment the experimental data. We discuss the challenges presented by shifting dimer-monomer proportions in determining the observable reaction orders and our mathematical treatment of such shifting in reactant structure.
Collapse
Affiliation(s)
- Kyle A Mack
- Department of Chemistry and Chemical Biology Baker Laboratory , Cornell University , Ithaca , New York 14853-1301 , United States
| | - David B Collum
- Department of Chemistry and Chemical Biology Baker Laboratory , Cornell University , Ithaca , New York 14853-1301 , United States
| |
Collapse
|
5
|
Reyes-Rodríguez GJ, Algera RF, Collum DB. Lithium Hexamethyldisilazide-Mediated Enolization of Acylated Oxazolidinones: Solvent, Cosolvent, and Isotope Effects on Competing Monomer- and Dimer-Based Pathways. J Am Chem Soc 2017; 139:1233-1244. [PMID: 28080036 PMCID: PMC6059651 DOI: 10.1021/jacs.6b11354] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Lithium hexamethyldisilazide (LiHMDS)-mediated enolization of (+)-4-benzyl-3-propionyl-2-oxazolidinone in THF-hydrocarbon mixtures shows unusual sensitivity to the choice of hydrocarbon cosolvent (hexane versus toluene) and to isotopic labeling. Four mechanisms corresponding to monosolvated monomers, trisolvated dimers, octasolvated monomers, and octasolvated dimers were identified. Even under conditions in which the LiHMDS monomer was the dominant observable form, dimer-based metalation was significant. The mechanism-dependent isotope and cosolvent effects are discussed in the context of ground-state stabilization and transition-state tunneling.
Collapse
Affiliation(s)
- Gabriel J. Reyes-Rodríguez
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853–1301
| | - Russell F. Algera
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853–1301
| | - David B. Collum
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853–1301
| |
Collapse
|
6
|
Ma Y, Algera RF, Collum DB. Sodium Diisopropylamide in N,N-Dimethylethylamine: Reactivity, Selectivity, and Synthetic Utility. J Org Chem 2016; 81:11312-11315. [PMID: 27768310 PMCID: PMC5242189 DOI: 10.1021/acs.joc.6b02287] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The reactivities and chemoselectivities of sodium diisopropylamide (NaDA) in N,N-dimethylethylamine (DMEA) are compared with those of lithium diisopropylamide (LDA) in tetrahydrofuran (THF). Metalations of arenes, epoxides, ketones, hydrazones, dienes, and alkyl and vinyl halides are represented. The positive attributes of NaDA-DMEA include high solubility, stability, resistance to solvent decomposition, and ease of preparation. The high reactivities and chemoselectivities often complement those of LDA-THF.
Collapse
Affiliation(s)
- Yun Ma
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
| | - Russell F. Algera
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
| | - David B. Collum
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
| |
Collapse
|
7
|
Liang J, Hoepker AC, Algera RF, Ma Y, Collum DB. Mechanism of Lithium Diisopropylamide-Mediated Ortholithiation of 1,4-Bis(trifluoromethyl)benzene under Nonequilibrium Conditions: Condition-Dependent Rate Limitation and Lithium Chloride-Catalyzed Inhibition. J Am Chem Soc 2015; 137:6292-303. [PMID: 25900574 PMCID: PMC4788392 DOI: 10.1021/jacs.5b01668] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Lithiation of 1,4-bis(trifluoromethyl)benzene with lithium diisopropylamide in tetrahydrofuran at -78 °C occurs under conditions at which the rates of aggregate exchanges are comparable to the rates of metalation. Under such nonequilibrium conditions, a substantial number of barriers compete to be rate limiting, making the reaction sensitive to trace impurities (LiCl), reactant concentrations, and isotopic substitution. Rate studies using the perdeuterated arene reveal odd effects of LiCl, including catalyzed rate acceleration at lower temperature and catalyzed rate inhibition at higher temperatures. The catalytic effects are accompanied by corresponding changes in the rate law. A kinetic model is presented that captures the critical features of the LiCl catalysis, focusing on the influence of LiCl-catalyzed re-aggregation of the fleeting monomer that can reside above, at, or below the equilibrium population without catalyst.
Collapse
Affiliation(s)
- Jun Liang
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853–1301
| | - Alexander C. Hoepker
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853–1301
| | - Russell F. Algera
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853–1301
| | - Yun Ma
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853–1301
| | - David B. Collum
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853–1301
| |
Collapse
|
8
|
Guang J, Liu QP, Hopson R, Williard PG. Lithium pinacolone enolate solvated by hexamethylphosphoramide. J Am Chem Soc 2015; 137:7347-56. [PMID: 25933508 DOI: 10.1021/jacs.5b01906] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report the crystal structure of a substoichiometric, HMPA-trisolvated lithium pinacolone enolate tetramer (LiOPin)4·HMPA3 abbreviated as T3. In this tetramer one HMPA binds to lithium more strongly than the other two causing a reduction in spatial symmetry with corresponding loss of C3 symmetry. A variety of NMR experiments, including HMPA titration, diffusion coefficient-formula weight (D-FW) analysis, and other multinuclear one- and two-dimensional NMR techniques reveal that T3 is the major species in hydrocarbon solution when more than 0.6 equiv of HMPA is present. Due to a small amount of moisture from HMPA or air leaking into the solution, a minor complex was identified and confirmed by X-ray diffraction analysis as a mixed aggregate containing enolate, lithium hydroxide, and HMPA in a 4:2:4 ratio, [(LiOPin)4·(LiOH)2·HMPA4], that we refer to as pseudo-T4. A tetra-HMPA-solvated lithium cyclopentanone enolate tetramer was also prepared and characterized by X-ray diffraction, leading to the conclusion that steric effects dominate the formation and solvation of the pinacolone aggregates. An unusual mixed aggregate consisting of pinacolone enolate, lithium diisopropyl amide, lithium oxide, and HMPA in the ratio 5:1:1:2 is also described.
Collapse
Affiliation(s)
- Jie Guang
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Qiyong Peter Liu
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Russell Hopson
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Paul G Williard
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| |
Collapse
|
9
|
Okutani M, Mori Y. Synthesis of Alkynes from Vinyl Triflates Using Tetrabutylammonium Fluoride. Chem Pharm Bull (Tokyo) 2015; 63:393-6. [DOI: 10.1248/cpb.c15-00146] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
| | - Yuji Mori
- Faculty of Pharmacy, Meijo University
| |
Collapse
|
10
|
George NS, Anderson KE, Barrett AGM. Total Synthesis of Cristatic Acid Based on Late-Stage Decarboxylative Allylic Migration and Biomimetic Aromatization of a Diketo Dioxinone. European J Org Chem 2013. [DOI: 10.1002/ejoc.201301102] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
11
|
Harrison-Marchand A, Mongin F. Mixed AggregAte (MAA): A Single Concept for All Dipolar Organometallic Aggregates. 1. Structural Data. Chem Rev 2013; 113:7470-562. [DOI: 10.1021/cr300295w] [Citation(s) in RCA: 145] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Anne Harrison-Marchand
- Laboratoire COBRA de l′Université de Rouen, INSA de Rouen, CNRS, UMR 6014 & FR 3038, IRCOF, Rue Tesnière, 76821 Mont St Aignan Cédex, France
| | - Florence Mongin
- Équipe Chimie et Photonique Moléculaires, Institut des Sciences Chimiques de Rennes, UMR 6226 CNRS-Université de Rennes 1, Bâtiment 10A, case 1003, Avenue du Général Leclerc, 35042 Rennes Cédex, France
| |
Collapse
|
12
|
Shulishov EV, Tomilov YV, Nefedov OM. Annelated 4,5-diazaspiro[2.4]hepta-4,6-diene obtained by [3 + 2] Cycloaddition of Diazocyclopropane to Cyclooctyne. MENDELEEV COMMUNICATIONS 2013. [DOI: 10.1016/j.mencom.2013.07.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
|
13
|
De Vries TS, Bruneau AM, Liou LR, Subramanian H, Collum DB. Azaaldol condensation of a lithium enolate solvated by N,N,N',N'-tetramethylethylenediamine: dimer-based 1,2-addition to imines. J Am Chem Soc 2013; 135:4103-9. [PMID: 23413774 PMCID: PMC3715612 DOI: 10.1021/ja400345c] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The lithium enolate of tert-amylacetate solvated by N,N,N',N'-tetramethylethylenediamine (TMEDA) is shown to be a doubly chelated dimer. Adding the dimeric enolate to 4-fluorobenzaldehyde-N-phenylimine affords an N-lithiated β-amino ester shown to be monomeric using (6)Li and (15)N NMR spectroscopies. Rate studies using (19)F NMR spectroscopy reveal reaction orders consistent with a transition structure of stoichiometry [(ROLi)2(TMEDA)2(imine)](‡). Density functional theory computations explore several possible dimer-based transition structures with monodentate and bidentate coordination of TMEDA. Supporting rate studies using trans-N,N,N',N'-1,2-tetramethylcyclohexanediamine showing analogous rates and rate law suggest that TMEDA is fully chelated.
Collapse
Affiliation(s)
- Timothy S. De Vries
- Department of Chemistry and Chemical Biology Baker Laboratory, Cornell University, Ithaca, New York 14853–1301
| | - Angela M. Bruneau
- Department of Chemistry and Chemical Biology Baker Laboratory, Cornell University, Ithaca, New York 14853–1301
| | - Lara R. Liou
- Department of Chemistry and Chemical Biology Baker Laboratory, Cornell University, Ithaca, New York 14853–1301
| | | | - David B. Collum
- Department of Chemistry and Chemical Biology Baker Laboratory, Cornell University, Ithaca, New York 14853–1301
| |
Collapse
|
14
|
Hoepker AC, Gupta L, Ma Y, Faggin MF, Collum DB. Regioselective lithium diisopropylamide-mediated ortholithiation of 1-chloro-3-(trifluoromethyl)benzene: role of autocatalysis, lithium chloride catalysis, and reversibility. J Am Chem Soc 2011; 133:7135-51. [PMID: 21500823 PMCID: PMC3102585 DOI: 10.1021/ja200906z] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Ortholithiation of 1-chloro-3-(trifluoromethyl)benzene with lithium diisopropylamide (LDA) in tetrahydrofuran at -78 °C displays characteristics of reactions in which aggregation events are rate limiting. Metalation with lithium-chloride-free LDA involves a rate-limiting deaggregation via dimer-based transition structures. The post-rate-limiting proton transfers are suggested to involve highly solvated triple ions. Autocatalysis by the resulting aryllithiums or catalysis by traces (<100 ppm) of LiCl diverts the reaction through di- and trisolvated monomer-based pathways for metalation at the 2 and 6 positions, respectively. The regiochemistry is dictated by a combination of kinetically controlled metalations overlaid by an equilibration involving diisopropylamine that is shown to occur by the microscopic reverse of the monomer-based metalations.
Collapse
Affiliation(s)
- Alexander C. Hoepker
- Department of Chemistry and Chemical Biology Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
| | - Lekha Gupta
- Department of Chemistry and Chemical Biology Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
| | - Yun Ma
- Department of Chemistry and Chemical Biology Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
| | - Marc F. Faggin
- Department of Chemistry and Chemical Biology Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
| | - David B. Collum
- Department of Chemistry and Chemical Biology Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
| |
Collapse
|
15
|
Gupta L, Ramírez A, Collum DB. Reaction of lithium diethylamide with an alkyl bromide and alkyl benzenesulfonate: origins of alkylation, elimination, and sulfonation. J Org Chem 2010; 75:8392-9. [PMID: 21077695 DOI: 10.1021/jo101505x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A combination of NMR, kinetic, and computational methods are used to examine reactions of lithium diethylamide in tetrahydrofuran (THF) with n-dodecyl bromide and n-octyl benzenesulfonate. The alkyl bromide undergoes competitive S(N)2 substitution and E2 elimination in proportions independent of all concentrations except for a minor medium effect. Rate studies show that both reactions occur via trisolvated-monomer-based transition structures. The alkyl benzenesulfonate undergoes competitive S(N)2 substitution (minor) and N-sulfonation (major) with N-sulfonation promoted at low THF concentrations. The S(N)2 substitution is shown to proceed via a disolvated monomer suggested computationally to involve a cyclic transition structure. The dominant N-sulfonation follows a disolvated-dimer-based transition structure suggested computationally to be a bicyclo[3.1.1] form. The differing THF and lithium diethylamide orders for the two reactions explain the observed concentration-dependent chemoselectivities.
Collapse
Affiliation(s)
- Lekha Gupta
- Department of Chemistry and Chemical Biology Baker Laboratory, Cornell University Ithaca, New York 14853-1301, United States
| | | | | |
Collapse
|
16
|
Ma Y, Hoepker AC, Gupta L, Faggin MF, Collum DB. 1,4-addition of lithium diisopropylamide to unsaturated esters: role of rate-limiting deaggregation, autocatalysis, lithium chloride catalysis, and other mixed aggregation effects. J Am Chem Soc 2010; 132:15610-23. [PMID: 20961095 PMCID: PMC2989387 DOI: 10.1021/ja105855v] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Lithium diisopropylamide (LDA) in tetrahydrofuran at -78 °C undergoes 1,4-addition to an unsaturated ester via a rate-limiting deaggregation of LDA dimer followed by a post-rate-limiting reaction with the substrate. Muted autocatalysis is traced to a lithium enolate-mediated deaggregation of the LDA dimer and the intervention of LDA-lithium enolate mixed aggregates displaying higher reactivities than LDA. Striking accelerations are elicited by <1.0 mol % LiCl. Rate and mechanistic studies have revealed that the uncatalyzed and catalyzed pathways funnel through a common monosolvated-monomer-based intermediate. Four distinct classes of mixed aggregation effects are discussed.
Collapse
Affiliation(s)
- Yun Ma
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
| | - Alexander C. Hoepker
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
| | - Lekha Gupta
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
| | - Marc F. Faggin
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
| | - David B. Collum
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
| |
Collapse
|
17
|
Cousins DM, Davidson MG, Frankis CJ, García-Vivó D, Mahon MF. Tris(2-dimethylaminoethyl)amine: a simple new tripodal polyamine ligand for Group 1 metals. Dalton Trans 2010; 39:8278-80. [DOI: 10.1039/c0dt00567c] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
18
|
Urbano J, Braga AAC, Maseras F, Álvarez E, Díaz-Requejo MM, Pérez PJ. The Mechanism of the Catalytic Functionalization of Haloalkanes by Carbene Insertion: An Experimental and Theoretical Study. Organometallics 2009. [DOI: 10.1021/om9006888] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Juan Urbano
- Laboratorio de Catálisis Homogénea, Departamento de Química y Ciencia de los Materiales, Unidad Asociada al CSIC, Campus de El Carmen s/n, Universidad de Huelva, 21007-Huelva, Spain
| | - Ataualpa A. C. Braga
- Institute of Chemical Research of Catalonia (ICIQ), 43007 Tarragona, Catalonia, Spain
| | - Feliu Maseras
- Institute of Chemical Research of Catalonia (ICIQ), 43007 Tarragona, Catalonia, Spain
| | - Eleuterio Álvarez
- Instituto de Investigaciones Químicas, CSIC-Universidad de Sevilla, Avenida Américo Vespucio 49, 41092 Sevilla, Spain
| | - M. Mar Díaz-Requejo
- Laboratorio de Catálisis Homogénea, Departamento de Química y Ciencia de los Materiales, Unidad Asociada al CSIC, Campus de El Carmen s/n, Universidad de Huelva, 21007-Huelva, Spain
| | - Pedro J. Pérez
- Laboratorio de Catálisis Homogénea, Departamento de Química y Ciencia de los Materiales, Unidad Asociada al CSIC, Campus de El Carmen s/n, Universidad de Huelva, 21007-Huelva, Spain
| |
Collapse
|
19
|
Okutani M, Mori Y. Conversion of Bromoalkenes into Alkynes by Wet Tetra-n-butylammonium Fluoride. J Org Chem 2008; 74:442-4. [DOI: 10.1021/jo802101a] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Masaru Okutani
- Faculty of Pharmacy, Meijo University, 150 Yagotoyama, Tempaku-ku, Nagoya 468-8503, Japan
| | - Yuji Mori
- Faculty of Pharmacy, Meijo University, 150 Yagotoyama, Tempaku-ku, Nagoya 468-8503, Japan
| |
Collapse
|
20
|
Kobayashi T, Ohmiya H, Yorimitsu H, Oshima K. Cobalt-catalyzed regioselective dehydrohalogenation of alkyl halides with dimethylphenylsilylmethylmagnesium chloride. J Am Chem Soc 2008; 130:11276-7. [PMID: 18671349 DOI: 10.1021/ja804277x] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cobalt-catalyzed reactions of haloalkanes with dimethylphenylsilylmethylmagnesium chloride result in highly regioselective dehydrohalogenation. The reaction does not follow the conventional E2 elimination mechanism but includes beta-hydride elimination from the corresponding alkylcobalt intermediate. The interesting reaction mechanism of the cobalt-catalyzed dehydrohalogenation offered unique transformations that are otherwise difficult to attain.
Collapse
Affiliation(s)
- Tsuneyuki Kobayashi
- Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoto-daigaku Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
| | | | | | | |
Collapse
|
21
|
Li D, Hopson R, Li W, Liu J, Williard PG. 13C INEPT diffusion-ordered NMR spectroscopy (DOSY) with internal references. Org Lett 2008; 10:909-11. [PMID: 18251549 PMCID: PMC3220947 DOI: 10.1021/ol703039v] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
13C INEPT Diffusion-ordered NMR spectroscopy (DOSY) with an internal reference system was developed to study the aggregation state of THF-solvated LDA dimeric complex. Six components are clearly identified in the diffusion dimension, and their DOSY-generated 13C INEPT spectrum slices agree extremely well with their respective INEPT spectra. The correlation between log D and log FW of the linear least-squares fit to reference points of all components is exceptionally high: (r = 0.9985).
Collapse
Affiliation(s)
- Deyu Li
- Department of Chemistry, Brown University, Providence, RI 02912 USA
| | - Russell Hopson
- Department of Chemistry, Brown University, Providence, RI 02912 USA
| | - Weibin Li
- Department of Chemistry, Brown University, Providence, RI 02912 USA
| | - Jia Liu
- Department of Chemistry, Brown University, Providence, RI 02912 USA
| | - Paul G. Williard
- Department of Chemistry, Brown University, Providence, RI 02912 USA
| |
Collapse
|
22
|
Wrackmeyer B, Klimkina EV, Milius W. Interannular Nitrogen-Lithium Bridges in Ferrocenophanes. Z Anorg Allg Chem 2008. [DOI: 10.1002/zaac.200700398] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
23
|
Blair VL, Clegg W, Conway B, Hevia E, Kennedy A, Klett J, Mulvey RE, Russo L. Alkali-metal-mediated manganationII of functionalized arenes and applications of ortho-manganated products in Pd-catalyzed cross-coupling reactions with iodobenzene. Chemistry 2008; 14:65-72. [PMID: 18033708 PMCID: PMC3781706 DOI: 10.1002/chem.200701597] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2007] [Accepted: 11/21/2007] [Indexed: 11/29/2022]
Abstract
Extending the recently introduced concept of "alkali-metal-mediated manganation" to functionalised arenes, the heteroleptic sodium manganate reagent [(tmeda)Na(tmp)(R)Mn(tmp)] (1; TMEDA=N,N,N',N'-tetramethylethylenediamine, TMP=2,2,6,6-tetramethylpiperidide, R=CH2SiMe3) has been treated with anisole or N,N-diisopropylbenzamide in a 1:1 stoichiometry in hexane. These reactions afforded the crystalline products [(tmeda)Na(tmp)(o-C6H4OMe)Mn(tmp)] (2) and [(tmeda)Na(tmp){o-{C(O)N(iPr)2C6H4}Mn(CH2SiMe3] (3), respectively, as determined from X-ray crystallographic studies. On the basis of these products, it can be surmised that reagent 1 has acted, at least partially and ultimately, as an alkyl base in the first reaction liberating the silane Me4Si, but as an amido base in the second reaction liberating the amine TMPH. Both of these paramagnetic products 2 and 3 have contacted ion-pair structures, the key features of which are six-atom, five-element (NaNMnCCO) and seven-atom, five-element (NaNMnCCCO) rings, respectively. Manganates 2 and 3 were successfully cross-coupled with iodobenzene under [PdCl(2)(dppf)] (dppf=1,1'-bis(diphenylphosphino)ferrocene) catalysis to generate unsymmetrical biaryl compounds in yields of 98.0 and 66.2 %, respectively. Emphasizing the importance of alkali-metal mediation in these manganation reactions, the bisalkyl Mn reagent on its own fails to metalate the said benzamide, but instead produces the monomeric, donor-acceptor complex [Mn(R)2{(iPr)2-NC(Ph)(==O)}2] (5), which has also been crystallographically characterised. During one attempt to repeat the synthesis of 2, the butoxide-contaminated complex [{(tmeda)Na(R)(OBu)(o-C6H4OMe)Mn}2] (6) was obtained. In contrast to 2 and 3, due to reduced steric constraints, this complex adopts a dimeric arrangement in the crystal, the centrepiece of which is a twelve atom (NaOCCMnC)2 ring.
Collapse
Affiliation(s)
- Victoria L Blair
- WestCHEM, Department of Pure and Applied Chemistry, University of StrathclydeGlasgow, G1 1XL, UK
| | - William Clegg
- School of Natural Sciences (Chemistry), Newcastle UniversityNewcastle upon Tyne, NE1 7RU, UK
| | - Ben Conway
- WestCHEM, Department of Pure and Applied Chemistry, University of StrathclydeGlasgow, G1 1XL, UK
| | - Eva Hevia
- WestCHEM, Department of Pure and Applied Chemistry, University of StrathclydeGlasgow, G1 1XL, UK
| | - Alan Kennedy
- WestCHEM, Department of Pure and Applied Chemistry, University of StrathclydeGlasgow, G1 1XL, UK
| | - Jan Klett
- WestCHEM, Department of Pure and Applied Chemistry, University of StrathclydeGlasgow, G1 1XL, UK
| | - Robert E Mulvey
- WestCHEM, Department of Pure and Applied Chemistry, University of StrathclydeGlasgow, G1 1XL, UK
| | - Luca Russo
- School of Natural Sciences (Chemistry), Newcastle UniversityNewcastle upon Tyne, NE1 7RU, UK
| |
Collapse
|
24
|
Chase PA, Lutz M, Spek AL, Gossage RA, van Koten G. Solid-state and solution structures of hetero-aggregates formed between nBuLi and NCN pincer aryl lithium. Dalton Trans 2008:5783-90. [DOI: 10.1039/b805092a] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
25
|
Ma Y, Collum DB. Lithium diisopropylamide-mediated reactions of imines, unsaturated esters, epoxides, and aryl carbamates: influence of hexamethylphosphoramide and ethereal cosolvents on reaction mechanisms. J Am Chem Soc 2007; 129:14818-25. [PMID: 17985891 DOI: 10.1021/ja074554e] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Several reactions mediated by lithium diisopropylamide (LDA) with added hexamethylphosphoramide (HMPA) are described. The N-isopropylimine of cyclohexanone lithiates via an ensemble of monomer-based pathways. Conjugate addition of LDA/HMPA to an unsaturated ester proceeds via di- and tetra-HMPA-solvated dimers. Deprotonation of norbornene epoxide by LDA/HMPA proceeds via an intermediate metalated epoxide as a mixed dimer with LDA. Ortholithiation of an aryl carbamate proceeds via a mono-HMPA-solvated monomer-based pathway. Dependencies on THF and other ethereal cosolvents suggest that secondary-shell solvation effects are important in some instances. The origins of the inordinate mechanistic complexity are discussed.
Collapse
Affiliation(s)
- Yun Ma
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, USA
| | | |
Collapse
|
26
|
Godenschwager PF, Collum DB. Lithium Hexamethyldisilazide-Mediated Enolizations: Influence of Chelating Ligands and Hydrocarbon Cosolvents on the Rates and Mechanisms. J Am Chem Soc 2007; 129:12023-31. [PMID: 17850084 DOI: 10.1021/ja074018m] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Enolizations of 2-methylcyclohexanone by lithium hexamethyldisilazide (LiHMDS) in the presence of three chelating ligands--trans-N,N,N',N'-tetramethylcyclohexanediamine, N,N,N',N'-tetramethylethylenediamine, and dimethoxyethane--reveal an approximate 40-fold range of rates. NMR spectroscopic analyses and rate studies reveal isostructural transition structures based on monomeric LiHMDS for the diamines. Rate studies of LiHMDS/dimethoxyethane-mediated enolizations implicate a substantial number of monomer- and dimer-based mechanisms. The rate laws vary for the three ligands because of ligand-dependent structural differences in both the reactants and the transition structures. The importance of LiHMDS-ketone complexes and the role of hydrocarbon cosolvents are discussed.
Collapse
Affiliation(s)
- Peter F Godenschwager
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University Ithaca, New York 14853-1301, USA
| | | |
Collapse
|
27
|
Tetrabutylammonium fluoride-induced dehydrobromination of vinyl bromides to terminal acetylenes. Tetrahedron Lett 2007. [DOI: 10.1016/j.tetlet.2007.07.174] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
28
|
Collum DB, McNeil AJ, Ramirez A. Lithium diisopropylamide: solution kinetics and implications for organic synthesis. Angew Chem Int Ed Engl 2007; 46:3002-17. [PMID: 17387670 DOI: 10.1002/anie.200603038] [Citation(s) in RCA: 169] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Lithium diisopropylamide (LDA) is a prominent reagent used in organic synthesis. In this Review, rate studies of LDA-mediated reactions are placed in the broader context of organic synthesis in three distinct segments. The first section provides a tutorial on solution kinetics, emphasizing the characteristic rate behavior caused by dominant solvation and aggregation effects. The second section summarizes substrate- and solvent-dependent mechanisms that reveal basic principles of solvation and aggregation. The final section suggests how an understanding of mechanism might be combined with empirical methods to optimize yields, rates, and selectivities of organolithium reactions and applied to organic synthesis.
Collapse
Affiliation(s)
- David B Collum
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, NY 14853-1301, USA.
| | | | | |
Collapse
|
29
|
Collum D, McNeil A, Ramirez A. Lithiumdiisopropylamid: Reaktionskinetik in Lösung und Folgerungen für die organische Synthese. Angew Chem Int Ed Engl 2007. [DOI: 10.1002/ange.200603038] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
30
|
Chadwick ST, Ramirez A, Gupta L, Collum DB. n-Butyllithium/N,N,N‘,N‘-Tetramethylethylenediamine-Mediated Ortholithiations of Aryl Oxazolines: Substrate-Dependent Mechanisms. J Am Chem Soc 2007; 129:2259-68. [PMID: 17269777 DOI: 10.1021/ja068057u] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
n-Butyllithium/N,N,N',N'-tetramethylethylenediamine-mediated ortholithiations of aryloxazolines are described. Methyl substituents on the aryloxazoline and substituents at the meta position of the arenes (methoxy, oxazolinyl, and fluoro) influence the rates and the mechanisms. Monomer- and dimer-based reactions are implicated. Density functional calculations probe details of the mechanism and suggest the origins of cooperative effects in meta-substituted aryl oxazolines.
Collapse
Affiliation(s)
- Scott T Chadwick
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, USA
| | | | | | | |
Collapse
|