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Direct Catalytic Asymmetric Conjugate Addition of Terminal Alkynes to α,β-Unsaturated Thioamides

2010; American Chemical Society; Volume: 132; Issue: 30 Linguagem: Inglês

10.1021/ja105141x

1943-2984

Ryo Yazaki, Naoya Kumagai, Masakatsu Shibasaki,

Sulfur-Based Synthesis Techniques

Direct catalytic asymmetric conjugate addition of terminal alkynes to alpha,beta-unsaturated thioamides under proton transfer conditions is described. Soft Lewis acid/hard Brønsted base cooperative catalysis is crucial for simultaneous activation of terminal alkynes and thioamides, affording the beta-alkynylthioamides in a highly enantioselective manner. Control experiments suggested that the intermediate copper thioamide enolate can work as Brønsted base to drive the catalytic cycle via proton transfer. The divergent transformation of the thioamide functionality highlights the synthetic utility of the alkynylation products.