Photoinduced metal-free cascade silylation/cyclization of alkynes/alkynones with hydrosilanes to access 3-silylated benzothiophenes and thioflavones.

A metal-free photocatalytic method for the synthesis of silylated thioflavones and benzothiophenes has been established through cascade silylation/cyclization of alkynes/alkynones with hydrosilanes. This transformation features mild reaction conditions, excellent functional group compatibility, and broad substrate scope. Moreover, this method can be readily applied to the late-stage silylation of structurally complex bioactive molecules, thus offering potential applications for pharmaceutical research. Mechanistic investigations indicate that this reaction proceeds through a radical pathway.