Brønsted acid-catalyzed solvent-controlled regioselective thiolation of 2-furylcarbinols†

Abstract

A novel p-toluenesulfonic acid-catalyzed solvent-controlled regioselective thiolation of 2-furylcarbinols for the efficient and chemoselective preparation of densely functionalized furan- and lactone-based sulfides under mild metal-free conditions has been developed. By using thiols as nucleophiles in DCE at 80 °C, a new reactivity involving a cascade C5-selective nucleophilic substitution/protonation–hydration/C–S bond cleavage/thia-Michael addition reaction leading to lactone-based sulfides rather than the known Piancatelli-type rearrangement products was revealed for the first time. This tunable thiolation protocol enables ready access to both furan- and lactone-based sulfide derivatives with excellent yields by the judicious choice of the reaction solvent.