From Propargylic Alcohols to Substituted Thiochromenes: -Disubstituent Effect in Intramolecular Alkyne Iodo/hydroarylation.

This work describes the 6-- cyclization of -aryl propargyl sulfides to afford 2-thiochromenes. The substitution at the propargylic position plays a crucial role in allowing intramolecular silver-catalyzed alkyne hydroarylation and -iodosuccinimide-promoted iodoarylation. Additionally, a PTSA-catalyzed thiolation reaction of propargylic alcohols was developed to synthesize the required tertiary -aryl propargyl ethers. The applicability of merging these two methods is demonstrated by synthesizing the retinoic acid receptor antagonist AGN194310.