Gold-catalyzed intramolecular carbothiolation of alkynes: Synthesis of 2,3-disubstituted benzothiophenes from (α-alkoxy alkyl) (ortho-alkynyl phenyl) sulfides

(Chemical Equation Presented) Gold forms rings: AuCl-catalyzed cyclization of (α-alkoxy alkyl) (ortho-alkynyl phenyl) Sulfides 1 proceeds under mild conditions to give 3-(α-alkoxy alkyl) benzothiophenes 2 in high yields for a wide range of substrates (see scheme). The starting materials are readily available through acetalization of ortho-bromobenzenethiol and subsequent Sonogashira coupling. This methodology provides an atom-economic route to sulfur-containing heteroarenes.