Pintus A, Rocchigiani L, Fernandez-Cestau J, Budzelaar PHM, Bochmann M. Stereo- and Regioselective Alkyne Hydrometallation with Gold(III) Hydrides.
Angew Chem Int Ed Engl 2016;
55:12321-4. [PMID:
27592697 PMCID:
PMC5113781 DOI:
10.1002/anie.201607522]
[Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Indexed: 11/10/2022]
Abstract
The hydroauration of internal and terminal alkynes by gold(III) hydride complexes [(C^N^C)AuH] was found to be mediated by radicals and proceeds by an unexpected binuclear outer-sphere mechanism to cleanly form trans-insertion products. Radical precursors such as azobisisobutyronitrile lead to a drastic rate enhancement. DFT calculations support the proposed radical mechanism, with very low activation barriers, and rule out mononuclear mechanistic alternatives. These alkyne hydroaurations are highly regio- and stereospecific for the formation of Z-vinyl isomers, with Z/E ratios of >99:1 in most cases.
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