1
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Schmalz V, Koert U. Visible-Light-Induced Photoannulation of α-Naphthyl Cyclopropane Carboxylic Esters to Functionalized Dihydrophenalenes. Org Lett 2021; 24:152-157. [PMID: 34932368 DOI: 10.1021/acs.orglett.1c03784] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
A general synthetic entry to functionalized dihydrophenalenes has been found using naphthyl-cyclopropane esters as starting materials. The desired annulation was possible with visible light, Ir(Fppy)3 as photocatalyst, BnNMe2 or DABCO as electron donor, HAT-catalyst, and proton source. A broad scope of substituted naphthyl and azanaphthyl derivatives provided the photoannulation products in high yield. Deuteration studies support a photoredox mechanism involving the photoreductive cyclopropane opening to an enolate radical followed by an aryl radical trapping.
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Affiliation(s)
- Veronika Schmalz
- Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Straße 4, D-35032 Marburg, Germany
| | - Ulrich Koert
- Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Straße 4, D-35032 Marburg, Germany
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2
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Agarwal RG, Coste SC, Groff BD, Heuer AM, Noh H, Parada GA, Wise CF, Nichols EM, Warren JJ, Mayer JM. Free Energies of Proton-Coupled Electron Transfer Reagents and Their Applications. Chem Rev 2021; 122:1-49. [PMID: 34928136 DOI: 10.1021/acs.chemrev.1c00521] [Citation(s) in RCA: 134] [Impact Index Per Article: 44.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
We present an update and revision to our 2010 review on the topic of proton-coupled electron transfer (PCET) reagent thermochemistry. Over the past decade, the data and thermochemical formalisms presented in that review have been of value to multiple fields. Concurrently, there have been advances in the thermochemical cycles and experimental methods used to measure these values. This Review (i) summarizes those advancements, (ii) corrects systematic errors in our prior review that shifted many of the absolute values in the tabulated data, (iii) provides updated tables of thermochemical values, and (iv) discusses new conclusions and opportunities from the assembled data and associated techniques. We advocate for updated thermochemical cycles that provide greater clarity and reduce experimental barriers to the calculation and measurement of Gibbs free energies for the conversion of X to XHn in PCET reactions. In particular, we demonstrate the utility and generality of reporting potentials of hydrogenation, E°(V vs H2), in almost any solvent and how these values are connected to more widely reported bond dissociation free energies (BDFEs). The tabulated data demonstrate that E°(V vs H2) and BDFEs are generally insensitive to the nature of the solvent and, in some cases, even to the phase (gas versus solution). This Review also presents introductions to several emerging fields in PCET thermochemistry to give readers windows into the diversity of research being performed. Some of the next frontiers in this rapidly growing field are coordination-induced bond weakening, PCET in novel solvent environments, and reactions at material interfaces.
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Affiliation(s)
- Rishi G Agarwal
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Scott C Coste
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Benjamin D Groff
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Abigail M Heuer
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Hyunho Noh
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Giovanny A Parada
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States.,Department of Chemistry, The College of New Jersey, Ewing, New Jersey 08628, United States
| | - Catherine F Wise
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Eva M Nichols
- Department of Chemistry, University of British Columbia, Vancouver, BC V6T 1Z1, Canada
| | - Jeffrey J Warren
- Department of Chemistry, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
| | - James M Mayer
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
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3
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Mazzanti S, Schritt C, ten Brummelhuis K, Antonietti M, Savateev A. Multisite PCET with photocharged carbon nitride in dark. EXPLORATION (BEIJING, CHINA) 2021; 1:20210063. [PMID: 37323696 PMCID: PMC10190955 DOI: 10.1002/exp.20210063] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Accepted: 11/15/2021] [Indexed: 06/17/2023]
Abstract
A combination of photochemistry and proton coupled electron transfer (PCET) is a primary strategy employed by biochemical systems and synthetic chemistry to enable uphill reactions under mild conditions. Degenerate nanometer-sized n-type semiconductor nanoparticles (SCNPs) with the Fermi level above the bottom of the conduction band are strongly reducing and act more like metals than semiconductors. Application of the degenerate SCNPs is limited to few examples. Herein, we load microporous potassium poly(heptazine imide) (K-PHI) nanoparticles with electrons (e‒) and charge balancing protons (H+) in an illumination phase using sacrificial agents. e‒/H+ in the K-PHI nanoparticles are weakly bound and therefore could be used in a range of PCET reactions in dark, such as generation of aryl radicals from aryl halides, ketyl radicals from ketones, and 6e‒/6H+ reduction of nitrobenzene to aniline. The integration of several features that until now were intrinsic for plants and natural photosynthesis into a transition metal free nanomaterial composed of abundant elements (C, N, and K) offers a powerful tool for synthetic organic chemistry.
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Affiliation(s)
- Stefano Mazzanti
- Max‐Planck Institute of Colloids and Interfaces, Department of Colloid ChemistryResearch Campus GolmPotsdamGermany
| | - Clara Schritt
- Max‐Planck Institute of Colloids and Interfaces, Department of Colloid ChemistryResearch Campus GolmPotsdamGermany
- Institut für Chemie und BiochemieFreie Universität BerlinBerlinGermany
| | - Katharina ten Brummelhuis
- Max‐Planck Institute of Colloids and Interfaces, Department of Colloid ChemistryResearch Campus GolmPotsdamGermany
| | - Markus Antonietti
- Max‐Planck Institute of Colloids and Interfaces, Department of Colloid ChemistryResearch Campus GolmPotsdamGermany
| | - Aleksandr Savateev
- Max‐Planck Institute of Colloids and Interfaces, Department of Colloid ChemistryResearch Campus GolmPotsdamGermany
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4
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Abstract
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SmI2 was introduced to organic chemistry as a single
electron transfer agent in 1977. After ca. 15 years of latency, the
scientific community has realized the high potential of this reagent,
and its chemistry has started blooming. This versatile reagent has
mediated a myriad of new bond formations, cyclizations, and other
reactions. Its popularity stems largely from the fact that three different
intermediates, radical anions, radicals, and anions, depending on
the ligand or additive used, could be obtained. Each of these intermediates
could in principle lead to a different product. While these options
vastly enrich the repertoire of SmI2, they necessitate
a thorough mechanistic understanding, especially concerning how appropriate
ligands direct the SmI2 to the desired intermediate. Our
first paper on this subject dealt with the reduction of an activated
double bond. The results were puzzling, especially the H/D isotope
effect, which depended on the order of the reagents addition. This
seminal paper was fundamental to an understanding of how the SmI2 works and enabled us to later explain various phenomena.
For example, it was found that in a given reaction, when MeOH is used
as a proton source, a spiro compound is obtained, while a bicyclic
product is obtained when t-BuOH is used. Our contribution
culminated in formulating guidelines for the rational use of proton
donors in SmI2 reactions. The need to understand
the complexity of the effect of additives
on various processes is nicely demonstrated in photoinduced reactions.
For example, hexamethylphosphoramide (HMPA) enhances the reduction
of anthracene while hampering the reaction of benzyl chloride. The
mechanistic understanding gained enabled us also to broaden the scope
of photostimulated reactions from substrates reacting by a dissociative
electron transfer mechanism to normal reductions, which are difficult
to accomplish at the ground state. Harnessing the classical knowledge
of proton transfer mechanisms to our SmI2 research enabled
us to decipher an old conundrum: why does the combination of water
and amine have such an enhancing effect on the reactivity of SmI2, which is not typical of these two when used separately.
In our studies on the affinity of ligands to SmI2, we discovered
that, in contradistinction to the accepted dogma, SmI2 is
much more azaphilic than it is oxophilic. On the basis of the size
difference between Sm3+ and Sm2+, we developed
a simple diagnostic tool for the nature of the steps following the
electron transfer. The reduction of imines showed that substrate affinity
to SmI2 plays also a crucial role. In these reactions,
new features such as autocatalysis and catalysis by quantum dots were
discovered. Several studies of the ligand effect lead to a clear formulation
of when an inner sphere or outer sphere electron transfer should be
expected. In addition, several reactions where proton-coupled electron
transfer (PCET) is the dominant mechanism were identified. Finally,
the surprisingly old tool of NMR “shift reagents” was
rediscovered and used to directly derive essential information on
the binding constants of ligands and substrates to SmI2.
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Affiliation(s)
- Shmaryahu Hoz
- Department of Chemistry and Institute for Nanotechnology & Advanced Materials, Bar-Ilan University, Ramat Gan 5290002, Israel
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5
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Li H, Hou Y, Liu C, Lai Z, Ning L, Szostak R, Szostak M, An J. Pentafluorophenyl Esters: Highly Chemoselective Ketyl Precursors for the Synthesis of α,α-Dideuterio Alcohols Using SmI2 and D2O as a Deuterium Source. Org Lett 2020; 22:1249-1253. [DOI: 10.1021/acs.orglett.9b04383] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Hengzhao Li
- College of Science, China Agricultural University, Beijing 100193, China
| | - Yuxia Hou
- College of Science, China Agricultural University, Beijing 100193, China
| | - Chengwei Liu
- Department of Chemistry, Rutgers University, 73 Warren Street, Newark, New Jersey 07102, United States
| | - Zemin Lai
- College of Science, China Agricultural University, Beijing 100193, China
| | - Lei Ning
- College of Science, China Agricultural University, Beijing 100193, China
| | - Roman Szostak
- Department of Chemistry, Wroclaw University, F. Joliot-Curie 14, Wroclaw 50-383, Poland
| | - Michal Szostak
- Department of Chemistry, Rutgers University, 73 Warren Street, Newark, New Jersey 07102, United States
| | - Jie An
- College of Science, China Agricultural University, Beijing 100193, China
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6
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Selective C-N σ Bond Cleavage in Azetidinyl Amides under Transition Metal-Free Conditions. Molecules 2019; 24:molecules24030459. [PMID: 30696043 PMCID: PMC6384560 DOI: 10.3390/molecules24030459] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Revised: 01/15/2019] [Accepted: 01/16/2019] [Indexed: 12/29/2022] Open
Abstract
Functionalization of amide bond via the cleavage of a non-carbonyl, C-N σ bond remains under-investigated. In this work, a transition-metal-free single-electron transfer reaction has been developed for the C-N σ bond cleavage of N-acylazetidines using the electride derived from sodium dispersions and 15-crown-5. Of note, less strained cyclic amides and acyclic amides are stable under the reaction conditions, which features the excellent chemoselectivity of the reaction. This method is amenable to a range of unhindered and sterically encumbered azetidinyl amides.
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7
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Chciuk TV, Anderson WR, Flowers RA. Interplay between Substrate and Proton Donor Coordination in Reductions of Carbonyls by SmI2–Water Through Proton-Coupled Electron-Transfer. J Am Chem Soc 2018; 140:15342-15352. [DOI: 10.1021/jacs.8b08890] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Tesia V. Chciuk
- Department of Chemistry, Lehigh University, 6 E. Packer Avenue, Bethlehem, Pennsylvania 18015, United States
| | - William R. Anderson
- Department of Chemistry, Lehigh University, 6 E. Packer Avenue, Bethlehem, Pennsylvania 18015, United States
| | - Robert A. Flowers
- Department of Chemistry, Lehigh University, 6 E. Packer Avenue, Bethlehem, Pennsylvania 18015, United States
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8
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Speckmeier E, Fuchs PJW, Zeitler K. A synergistic LUMO lowering strategy using Lewis acid catalysis in water to enable photoredox catalytic, functionalizing C-C cross-coupling of styrenes. Chem Sci 2018; 9:7096-7103. [PMID: 30310630 PMCID: PMC6137453 DOI: 10.1039/c8sc02106f] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2018] [Accepted: 07/17/2018] [Indexed: 12/12/2022] Open
Abstract
Easily available α-carbonyl acetates serve as convenient alkyl radical source for an efficient, photocatalytic cross-coupling with a great variety of styrenes. Activation of electronically different α-acetylated acetophenone derivatives could be effected via LUMO lowering catalysis using a superior, synergistic combination of water and (water-compatible) Lewis acids. Deliberate application of fac-Ir(ppy)3 as photocatalyst to enforce an oxidative quenching cycle is crucial to the success of this (umpolung type) transformation. Mechanistic particulars of this dual catalytic coupling reaction have been studied in detail using both Stern-Volmer and cyclic voltammetry experiments. As demonstrated in more than 30 examples, our water-assisted LA/photoredox catalytic activation strategy allows for excess-free, equimolar radical cross-coupling and subsequent formal Markovnikov hydroxylation to versatile 1,4-difunctionalized products in good to excellent yields.
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Affiliation(s)
- Elisabeth Speckmeier
- Institut für Organische Chemie , Universität Leipzig , Johannisallee 29 , D-04103 Leipzig , Germany .
| | - Patrick J W Fuchs
- Institut für Organische Chemie , Universität Leipzig , Johannisallee 29 , D-04103 Leipzig , Germany .
| | - Kirsten Zeitler
- Institut für Organische Chemie , Universität Leipzig , Johannisallee 29 , D-04103 Leipzig , Germany .
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9
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Yang JD, Ji P, Xue XS, Cheng JP. Recent Advances and Advisable Applications of Bond Energetics in Organic Chemistry. J Am Chem Soc 2018; 140:8611-8623. [DOI: 10.1021/jacs.8b04104] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Jin-Dong Yang
- Center of Basic Molecular Science (CBMS), Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Pengju Ji
- Center of Basic Molecular Science (CBMS), Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Xiao-Song Xue
- State Key Laboratory of Elemento-organic Chemistry, Collaborative Innovation Centre of Chemical Science and Engineering, College of Chemistry, Nankai University, Tianjin 300071, China
| | - Jin-Pei Cheng
- Center of Basic Molecular Science (CBMS), Department of Chemistry, Tsinghua University, Beijing 100084, China
- State Key Laboratory of Elemento-organic Chemistry, Collaborative Innovation Centre of Chemical Science and Engineering, College of Chemistry, Nankai University, Tianjin 300071, China
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10
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Lei P, Ding Y, Zhang X, Adijiang A, Li H, Ling Y, An J. A Practical and Chemoselective Ammonia-Free Birch Reduction. Org Lett 2018; 20:3439-3442. [PMID: 29846078 DOI: 10.1021/acs.orglett.8b00891] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A novel protocol for a significantly improved, practical, and chemoselective ammonia-free Birch reduction mediated by bench-stable sodium dispersions and recoverable 15-crown-5 ether is reported. A broad range of aromatic and heteroaromatic compounds is reduced with excellent yields.
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Affiliation(s)
- Peng Lei
- College of Science , China Agricultural University , No. 2 Yuanmingyuan West Road , Beijing 100193 , China
| | - Yuxuan Ding
- College of Science , China Agricultural University , No. 2 Yuanmingyuan West Road , Beijing 100193 , China
| | - Xiaohe Zhang
- College of Science , China Agricultural University , No. 2 Yuanmingyuan West Road , Beijing 100193 , China
| | - Adila Adijiang
- College of Science , China Agricultural University , No. 2 Yuanmingyuan West Road , Beijing 100193 , China
| | - Hengzhao Li
- College of Science , China Agricultural University , No. 2 Yuanmingyuan West Road , Beijing 100193 , China
| | - Yun Ling
- College of Science , China Agricultural University , No. 2 Yuanmingyuan West Road , Beijing 100193 , China
| | - Jie An
- College of Science , China Agricultural University , No. 2 Yuanmingyuan West Road , Beijing 100193 , China
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11
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Zhang B, Li H, Ding Y, Yan Y, An J. Reduction and Reductive Deuteration of Tertiary Amides Mediated by Sodium Dispersions with Distinct Proton Donor-Dependent Chemoselectivity. J Org Chem 2018; 83:6006-6014. [PMID: 29750511 DOI: 10.1021/acs.joc.8b00617] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
A practical and scalable single electron transfer reduction mediated by sodium dispersions has been developed for the reduction and reductive deuteration of tertiary amides. The chemoselectivity of this method highly depends on the nature of the proton donor. The challenging reduction via C-N bond cleavage has been achieved using Na/EtOH, affording alcohol products, while the use of Na/NaOH/H2O leads to the formation of amines via selective C-O scission. Sodium dispersions with high specific surface areas are crucial to obtain high yields and good chemoselectivity. This new method tolerates a range of tertiary amides. Moreover, the corresponding reductive deuterations mediated by Na/EtOD- d1 and Na/NaOH/D2O afford useful α,α-dideuterio alcohols and α,α-dideuterio amines with an excellent deuterium content.
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Affiliation(s)
- Bin Zhang
- College of Science , China Agricultural University , No. 2 Yuanmingyuan West Road , Beijing 100193 , China
| | - Hengzhao Li
- College of Science , China Agricultural University , No. 2 Yuanmingyuan West Road , Beijing 100193 , China
| | - Yuxuan Ding
- College of Science , China Agricultural University , No. 2 Yuanmingyuan West Road , Beijing 100193 , China
| | - Yuhao Yan
- College of Science , China Agricultural University , No. 2 Yuanmingyuan West Road , Beijing 100193 , China
| | - Jie An
- College of Science , China Agricultural University , No. 2 Yuanmingyuan West Road , Beijing 100193 , China
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12
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Han M, Ding Y, Yan Y, Li H, Luo S, Adijiang A, Ling Y, An J. Transition-Metal-Free, Selective Reductive Deuteration of Terminal Alkynes with Sodium Dispersions and EtOD- d 1. Org Lett 2018; 20:3010-3013. [PMID: 29733218 DOI: 10.1021/acs.orglett.8b01036] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
A transition-metal-free single electron transfer reaction has been developed for the synthesis of [D3]-alkenes from terminal alkynes using sodium dispersions as the electron donor and EtOD- d1 as the deuterium source. Both reagents are cost-effective and bench-stable. This practical method exhibits remarkable terminal alkyne selectivity and exclusive alkene selectivity. Excellent deuterium incorporations and yields were achieved across a broad range of terminal alkynes without olefin isomerization. Of note, this reaction is highly solvent dependent. n-Hexane provides unique enhancement to this reductive deuteration process.
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Affiliation(s)
- Minhui Han
- College of Science , China Agricultural University , No. 2 Yuanmingyuan West Road , Beijing 100193 , China
| | - Yuxuan Ding
- College of Science , China Agricultural University , No. 2 Yuanmingyuan West Road , Beijing 100193 , China
| | - Yuhao Yan
- College of Science , China Agricultural University , No. 2 Yuanmingyuan West Road , Beijing 100193 , China
| | - Hengzhao Li
- College of Science , China Agricultural University , No. 2 Yuanmingyuan West Road , Beijing 100193 , China
| | - Shihui Luo
- College of Science , China Agricultural University , No. 2 Yuanmingyuan West Road , Beijing 100193 , China
| | - Adila Adijiang
- College of Science , China Agricultural University , No. 2 Yuanmingyuan West Road , Beijing 100193 , China
| | - Yun Ling
- College of Science , China Agricultural University , No. 2 Yuanmingyuan West Road , Beijing 100193 , China
| | - Jie An
- College of Science , China Agricultural University , No. 2 Yuanmingyuan West Road , Beijing 100193 , China
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13
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Synthesis of Nitrogen Heterocycles Using Samarium(II) Iodide. Molecules 2017; 22:molecules22112018. [PMID: 29160806 PMCID: PMC6150357 DOI: 10.3390/molecules22112018] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Revised: 11/11/2017] [Accepted: 11/13/2017] [Indexed: 11/19/2022] Open
Abstract
Nitrogen heterocycles represent vital structural motifs in biologically-active natural products and pharmaceuticals. As a result, the development of new, convenient and more efficient processes to N-heterocycles is of great interest to synthetic chemists. Samarium(II) iodide (SmI2, Kagan’s reagent) has been widely used to forge challenging C–C bonds through reductive coupling reactions. Historically, the use of SmI2 in organic synthesis has been focused on the construction of carbocycles and oxygen-containing motifs. Recently, significant advances have taken place in the use of SmI2 for the synthesis of nitrogen heterocycles, enabled in large part by the unique combination of high reducing power of this reagent (E1/2 of up to −2.8 V) with excellent chemoselectivity of the reductive umpolung cyclizations mediated by SmI2. In particular, radical cross-coupling reactions exploiting SmI2-induced selective generation of aminoketyl radicals have emerged as concise and efficient methods for constructing 2-azabicycles, pyrrolidines and complex polycyclic barbiturates. Moreover, a broad range of novel processes involving SmI2-promoted formation of aminyl radicals have been leveraged for the synthesis of complex nitrogen-containing molecular architectures by direct and tethered pathways. Applications to the synthesis of natural products have highlighted the generality of processes and the intermediates accessible with SmI2. In this review, recent advances involving the synthesis of nitrogen heterocycles using SmI2 are summarized, with a major focus on reductive coupling reactions that enable one-step construction of nitrogen-containing motifs in a highly efficient manner, while taking advantage of the spectacular selectivity of the venerable Kagan’s reagent.
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14
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Kolmar SS, Mayer JM. SmI 2(H 2O) n Reduction of Electron Rich Enamines by Proton-Coupled Electron Transfer. J Am Chem Soc 2017; 139:10687-10692. [PMID: 28718640 PMCID: PMC5812026 DOI: 10.1021/jacs.7b03667] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Samarium diiodide in the presence of water and THF (SmI2(H2O)n) has in recent years become a versatile and useful reagent, mainly for reducing carbonyl-type substrates. This work reports the reduction of several enamines by SmI2(H2O)n. Mechanistic experiments implicate a concerted proton-coupled electron transfer (PCET) pathway, based on various pieces of evidence against initial outer-sphere electron transfer, proton transfer, or substrate coordination. A thermochemical analysis indicates that the C-H bond formed in the rate-determining step has a bond dissociation free energy (BDFE) of ∼32 kcal mol-1. The O-H BDFE of the samarium aquo ion is estimated to be 26 kcal mol-1, which is among the weakest known X-H bonds of stable reagents. Thus, SmI2(H2O)n should be able to form very weak C-H bonds. The reduction of these highly electron rich substrates by SmI2(H2O)n shows that this reagent is a very strong hydrogen atom donor as well as an outer-sphere reductant.
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Affiliation(s)
- Scott S. Kolmar
- Department of Chemistry, Yale University, New Haven, Connecticut, 06520
| | - James M. Mayer
- Department of Chemistry, Yale University, New Haven, Connecticut, 06520
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15
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Li H, Zhang B, Dong Y, Liu T, Zhang Y, Nie H, Yang R, Ma X, Ling Y, An J. A selective and cost-effective method for the reductive deuteration of activated alkenes. Tetrahedron Lett 2017. [DOI: 10.1016/j.tetlet.2017.05.092] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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16
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Huq SR, Shi S, Diao R, Szostak M. Mechanistic Study of SmI2/H2O and SmI2/Amine/H2O-Promoted Chemoselective Reduction of Aromatic Amides (Primary, Secondary, Tertiary) to Alcohols via Aminoketyl Radicals. J Org Chem 2017. [DOI: 10.1021/acs.joc.7b00372] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Syed R. Huq
- Department of Chemistry, Rutgers University, 73 Warren Street, Newark, New Jersey 07102, United States
| | - Shicheng Shi
- Department of Chemistry, Rutgers University, 73 Warren Street, Newark, New Jersey 07102, United States
| | - Ray Diao
- Department of Chemistry, Rutgers University, 73 Warren Street, Newark, New Jersey 07102, United States
| | - Michal Szostak
- Department of Chemistry, Rutgers University, 73 Warren Street, Newark, New Jersey 07102, United States
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17
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Han M, Ma X, Yao S, Ding Y, Yan Z, Adijiang A, Wu Y, Li H, Zhang Y, Lei P, Ling Y, An J. Development of a Modified Bouveault–Blanc Reduction for the Selective Synthesis of α,α-Dideuterio Alcohols. J Org Chem 2017; 82:1285-1290. [PMID: 28029787 DOI: 10.1021/acs.joc.6b02950] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Minhui Han
- College of Science, China Agricultural University, No. 2 Yuanmingyuan West Road, Beijing 100193, China
| | - Xiaodong Ma
- College of Science, China Agricultural University, No. 2 Yuanmingyuan West Road, Beijing 100193, China
| | - Shangchu Yao
- College of Science, China Agricultural University, No. 2 Yuanmingyuan West Road, Beijing 100193, China
| | - Yuxuan Ding
- College of Science, China Agricultural University, No. 2 Yuanmingyuan West Road, Beijing 100193, China
| | - Zihan Yan
- College of Science, China Agricultural University, No. 2 Yuanmingyuan West Road, Beijing 100193, China
| | - Adila Adijiang
- College of Science, China Agricultural University, No. 2 Yuanmingyuan West Road, Beijing 100193, China
| | - Yufei Wu
- College of Science, China Agricultural University, No. 2 Yuanmingyuan West Road, Beijing 100193, China
| | - Hengzhao Li
- College of Science, China Agricultural University, No. 2 Yuanmingyuan West Road, Beijing 100193, China
| | - Yuntong Zhang
- College of Science, China Agricultural University, No. 2 Yuanmingyuan West Road, Beijing 100193, China
| | - Peng Lei
- College of Science, China Agricultural University, No. 2 Yuanmingyuan West Road, Beijing 100193, China
| | - Yun Ling
- College of Science, China Agricultural University, No. 2 Yuanmingyuan West Road, Beijing 100193, China
| | - Jie An
- College of Science, China Agricultural University, No. 2 Yuanmingyuan West Road, Beijing 100193, China
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