Regioselective Synthesis of Dihydrothiophenes and Thiophenes via the Rhodium-Catalyzed Transannulation of 1,2,3-Thiadiazoles with Alkenes

A method
for the regioselective synthesis of a wide range of dihydrothiophenes
was developed from the rhodium-catalyzed transannulation of 1,2,3-thiadiazoles
with aliphatic, aromatic, and heteroaromatic alkenes. Tandem rhodium-catalyzed
transannulation of 1,2,3-thiadiazoles with alkenes followed by 2,3-dichloro-5,6-dicyano-1,4-benzoquinone
(DDQ) oxidation was also demonstrated for the one-pot regioselective
synthesis of various thiophenes. Advantages of the present method
include a broad substrate scope, wide functional group compatibility,
and high regioselectivity.