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

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 alpha-indol-3-yl alpha-((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.

Automated summary

The gold-catalyzed transformation of propargylic glycols with thiols results in the formation of alpha-indol-3-yl alpha-((Z)-2-thioalkenyl) ketones through a complex but selective reaction mechanism. This sequence involves regioselective thiolation of indolyl diols followed by the attack of sulfur on the activated alkyne, rather than the indole. The final compounds are obtained in high yields from simple starting materials such as indolyl acyloins, ethynyl magnesium bromide, and thiols.