Visible light-mediated <i>ipso</i>-annulation of activated alkynes: access to 3-alkylated spiro[4,5]-trienones, thiaspiro[4,5]-trienones and azaspiro[4,5]-trienones

Abstract

A novel method for chemoselective difunctionalization of activated alkynes for synthesizing 3-alkylated spiro[4,5]-trienones, thiaspiro[4,5]-trienones and spirolactams has been uncovered using photoredox catalysis under visible light conditions. The rarely used tricarbonyl compounds in photoredox catalysis were used as the alkylating source. A remarkable functional group tolerance was observed, and the application of the method has been showcased by transforming tricarbonylated spirolactams to their corresponding monocarbonylated products, which are difficult to access using traditional methods.