Addition of Benzenethiols to Silicon-Containing Enynes and Enynones

Propynylidene derivatives of dimethyl malonate and Meldrumʼs acid, as well as cross-conjugated enynones, containing Me₃Si, Et₃Si, and t-BuMe₂Si groups reacted with 4-methyl-, 4-methoxy-, and 4-chloro­benzenethiol under basic conditions to give the corresponding addition products with buta-1,3-diene and penta-1,4-dien-3-one fragments with high stereoselectivity. The thiylation products of enyne derivatives of dimethyl malonate and Meldrumʼs acid retain the trialkylsilyl group, whereas the addition of benzenethiols to 5-(tri­alkylsilyl)-1-phenylpent-1-en-4-yn-3-ones is accompanied by desilylation. Some mechanistic features of the described reactions have been established, and methods for the stereoselective synthesis of sulfur-containing polyunsaturated compounds have been developed.