Old Reagent for a Trick in the Stereoselective Hydromethylation of Alkynes Enabled by Cu(I) Photosensitizer Catalysis

Herein, an unprecedented exploitation of α-silyl amine as a methyl radical equivalent for the reaction with alkynes has been realized, providing practical access to trisubstituted alkenes with exclusive regioselectivity and generally high E / Z diastereoselectivity. This photoredox protocol features Cu(I) photosensitizer catalysis, mild reaction conditions, and sequential C–Si and C–N bond cleavage. Notably, this transformation unveils a novel reactivity mode of an old reagent and represents a rare example of catalytic alkyne hydromethylation.