Carbozincation Reactions of Carbon–Carbon Multiple Bonds

Sklute, Genia; Cavender, Hannah; Marek, Ilan

doi:10.1002/0471264180.or087.03

Cited by 7 publications

(2 citation statements)

References 202 publications

(211 reference statements)

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“…Catalytic alkyne carbozincation can be accomplished under mild conditions with controllable chemoselectivity, regioselectivity, and stereoselectivity. Although this promising method is attracting increasing attention, two problems hamper its further development. First, although methods for carbozincation of internal alkynes are well established, reactions of terminal alkynes remain challenging because the highly acidic proton of these compounds can react with basic zinc reagents and destroy active catalysts.…”

Section: Introductionmentioning

confidence: 99%

Iron-Catalyzed Vinylzincation of Terminal Alkynes

Huang

Sun

et al. 2021

J. Am. Chem. Soc.

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Organozinc reagents are among the most commonly used organometallic reagents in modern synthetic chemistry, and multifunctionalized organozinc reagents can be synthesized from structurally simple, readily available ones by means of alkyne carbozincation. However, this method suffers from poor tolerance for terminal alkynes, and transformation of the newly introduced organic groups is difficult, which limits its applications. Herein, we report a method for vinylzincation of terminal alkynes catalyzed by newly developed iron catalysts bearing 1,10-phenanthroline-imine ligands. This method provides efficient access to novel organozinc reagents with a diverse array of structures and functional groups from readily available vinylzinc reagents and terminal alkynes. The method features excellent functional group tolerance (tolerated functional groups include amino, amide, cyano, ester, hydroxyl, sulfonyl, acetal, phosphono, pyridyl), a good substrate scope (suitable terminal alkynes include aryl, alkenyl, and alkyl acetylenes bearing various functional groups), and high chemoselectivity, regioselectivity, and stereoselectivity. The method could significantly improve the synthetic efficiency of various important bioactive molecules, including vitamin A. Mechanistic studies indicate that the new iron-1,10-phenanthroline-imine catalysts developed in this study have an extremely crowded reaction pocket, which promotes efficient transfer of the vinyl group to the alkynes, disfavors substitution reactions between the zinc reagent and the terminal C−H bond of the alkynes, and prevents the further reactions of the products. Our findings show that iron catalysts can be superior to other metal catalysts in terms of activity, chemoselectivity, regioselectivity, and stereoselectivity when suitable ligands are used.

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Section: Introductionmentioning

confidence: 99%

Iron-Catalyzed Vinylzincation of Terminal Alkynes

Huang

Sun

et al. 2021

J. Am. Chem. Soc.

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“…The result shown in eq 3 suggests that the electron-donating group in R 1 enhances the coordination ability of the alkyne moiety ( A ) to accelerate the carbozincation. Many carbozincations of alkynes have been established to date . However, most involve transition-metal-catalyzed syn -carbozincation and require an organozinc reagent that is prepared either in advance or in situ.…”

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confidence: 99%