Mechanism of -Selective Hydroalkylation of Terminal Alkynes

Overview

Journal J Am Chem Soc

Publisher American Chemical Society

Specialty Chemistry

Date 2021 Sep 30

PMID 34587735

Authors

Mitchell T Lee

Gojko Lalic

Affiliations

Soon will be listed here.

Abstract

This paper describes a detailed mechanistic study of the silver-catalyzed Z-selective hydroalkylation of terminal alkynes. Considering the established mechanistic paradigms for -selective hydroalkylation of alkynes, we explored a mechanism based on the radical carbometalation of alkynes. Experimental results have provided strong evidence against the initially proposed radical mechanism and have led us to propose a new mechanism for the -selective hydroalkylation of alkynes based on boronate formation and a 1,2-metalate shift. The new mechanism provides a rationale for the excellent Z-selectivity observed in the reaction. A series of stoichiometric experiments has probed the feasibility of the proposed elementary steps and revealed an additional role of the silver catalyst in the protodeboration of an intermediate. Finally, a series of kinetic measurements, KIE experiments, and competition experiments allowed us to identify the turnover limiting step and the resting state of the catalyst. We believe that the results of this study will be useful in the further exploration and development of related transformations of alkynes.

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