Gold-Catalyzed Reactions of 2-Alkynyl-1-indolyl-1,2-diols with Thiols: Stereoselective Synthesis of (Z)-α-Indol-3-yl α-(2-Thioalkenyl) Ketones

Abstract

Propargylic glycols, 2-alkynyl-1-(indol-3-yl)-1,2-diols, react with thiols undergoing a complex but selective gold-catalyzed transformation that gives rise to α-indol-3-yl α-((Z)-2-thioalkenyl) ketones. The sequence is triggered by the regioselective thiolation of indolyl diols followed by an attack of the sulfur instead of the indole over the activated alkyne. The final compounds are obtained in remarkably high yields and arise from simple starting materials such as indolyl acyloins, ethynyl magnesium bromide and thiols.