Stereospecific and stereoconvergent nucleophilic substitution reactions at tertiary carbon centers

Zhang, Xin; Tan, Choon‐Hong

doi:10.1016/j.chempr.2020.11.022

Cited by 58 publications

(25 citation statements)

References 114 publications

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“… 3 Even more challenging is the preparation of vicinal stereocenter B that is only constituted of carbons and hydrogen atoms (hydrocarbon chains) and therefore devoid of polar functions ( Scheme 1 ), 4 which are usually required as a chemical handle to perform selective transformations, eliminating most of the synthetically powerful [3,3]-sigmatropic rearrangements 5 and enolate approaches. 6 While the nucleophilic substitution reaction at primary, secondary, 7 and even at tertiary stereocenters 8 are well explored with carbon nucleophiles, nucleophilic substitution at quaternary carbon stereocenter with carbon nucleophile has never been considered since the amount of energy required to break a C–C single bond is too high (bond energy 348 kJ/mol). Is, nevertheless, the nucleophilic substitution at a quaternary carbon center a conceivable process?…”

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confidence: 99%

Stereospecific Construction of Quaternary Carbon Stereocenters from Quaternary Carbon Stereocenters

2022

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Stereospecific Construction of Quaternary Carbon Stereocenters from Quaternary Carbon Stereocenters

2022

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“…Mechanistic studies suggest that this reaction involves Mn-catalyzed alkyl radical formation and subsequent azidyl group transfer through Mn III/IV electrocatalysis, which avoids the oxidation to carbocation thus minimizing the side reactions leading to oxygenated products. In addition to these new research articles, we also found a few new review articles that were published during the manuscript review process. − …”

Section: Literature Updates: Additions Made During Manuscript Revisionmentioning

confidence: 99%

New Strategies for the Synthesis of Aliphatic Azides

2021

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Aliphatic azides are a versatile class of compounds found in a variety of biologically active pharmaceuticals. These compounds are also recognized as useful precursors for the synthesis of a range of nitrogen-based scaffolds of therapeutic drugs, biologically active compounds, and functional materials. In light of the growing importance of aliphatic azides in both chemical and biological sciences, a vast array of synthetic strategies for the preparation of structurally diverse aliphatic azides have been developed over the past decades. However, to date, this topic has not been the subject of a dedicated review. This review aims to provide a concise overview of modern synthetic strategies to access aliphatic azides that have emerged since 2010. The discussed azidation reactions include (a) azidation of C–C multiple bonds, (b) azidation of C–H bonds, (c) the direct transformation of vinyl azides into other aliphatic azides, and (d) miscellaneous reactions to access aliphatic azides. We critically discuss the synthetic outcomes and the generality and uniqueness of the different mechanistic rationale of each of the selected reactions. The challenges and potential opportunities of the topic are outlined.

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“…In particular, the assembly of sterically congested ethers/amines are of intense interests. However, conventional methods to access these targets always faces daunting challenges 2 . While the venerable S N 2 reactions as exemplified by Williamson ether synthesis 3 , 4 and Mitsunobu reaction 5 , 6 are virtually straightforward, they are, however, heavily restricted to primary and secondary alkyl electrophiles.…”

Section: Introductionmentioning

confidence: 99%

Photoredox-catalyzed C–C bond cleavage of cyclopropanes for the formation of C(sp3)–heteroatom bonds

Zhang

Pan

et al. 2022

Nat Commun

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Sterically congested C–O and C–N bonds are ubiquitous in natural products, pharmaceuticals, and bioactive compounds. However, the development of a general method for the efficient construction of those sterically demanding covalent bonds still remains a formidable challenge. Herein, a photoredox-driven ring-opening C(sp3)–heteroatom bond formation of arylcyclopropanes is presented, which enables the construction of structurally diversified while sterically congested dialkyl ether, alkyl ester, alcohol, amine, chloride/fluoride, azide and also thiocyanate derivatives. The selective single electron oxidation of aryl motif associated with the thermodynamic driving force from ring strain-release is the key for this transformation. By this synergistic activation mode, C–C bond cleavage of otherwise inert cyclopropane framework is successfully unlocked. Further mechanistic and computational studies disclose a complete stereoinversion upon nucleophilic attack, thus proving a concerted SN2-type ring-opening functionalization manifold, while the regioselectivity is subjected to an orbital control scenario.

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Stereospecific and stereoconvergent nucleophilic substitution reactions at tertiary carbon centers

Cited by 58 publications

References 114 publications

Stereospecific Construction of Quaternary Carbon Stereocenters from Quaternary Carbon Stereocenters

Stereospecific Construction of Quaternary Carbon Stereocenters from Quaternary Carbon Stereocenters

New Strategies for the Synthesis of Aliphatic Azides

Photoredox-catalyzed C–C bond cleavage of cyclopropanes for the formation of C(sp3)–heteroatom bonds

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