Alkyne/thio umpolung tactic replacement: synthesis of alkynyl sulfides via capturing the in situ formed alkynylthiolate anion

Abstract

Alkynyl sulfides are prevalent in bioactive molecules and functional materials. A variety of methods for the construction of alkynyl sulfides have been developed; however, a general and practical synthetic strategy to obtain alkynyl sulfides from readily available starting materials remains non-trivial. Herein, we report the widely accessible 1,2,3-thiadiazoles as robust alkynylthiolate anions, which couple with C(sp^1–3)-electrophiles to construct the corresponding alkynyl sulfides in the presence of a metal catalyst or under metal free conditions (79 examples with an average yield of 68%). The alkynylthiolation reaction with aryl iodides and bromoalkynes is experimentally easy to perform under mild conditions in the presence of palladium or copper catalysts; the alkynylthiolation with 1°- and 2°-alkyl electrophiles and a difluorocarbene precursor is performed under metal free conditions. Gram-scale reactions and diverse synthetic transformations convincingly demonstrate the synthetic potential of this method.