Palladium-catalyzed Decarboxylative Cycloaddition Of Vinyl Ethylene Carbonate With Isothiocyanate

In recent years,palladium catalyzed decarboxylation has become an important method to construct chiral quaternary carbon centers and heterocyclic compounds.Vinylethylene carbonates?VECs?can form zwitterionic?-allyl palladium intermediate by Pd-catalyst,which can trigger various conversions to form allylic products or heterocyclic compounds.The transformation of VECs has been an attractive research topic.1,3-Oxazole-2-thione derivatives are an important class of five-membered heterocyclic compounds with unique biological activities,which are widely used in pharmaceutical synthesis.Currently,the synthetic methods of 1,3-oxazole-2-thione derivatives are under development,such as limited substrates scope or complicated synthetic routes.The decarboxylative cycloaddition of VEC and isothiocyanate catalyzed by palladiu m catalysts was investigated.The reactions proceeded smoothly in the presence of5 mol%Pd₂?dba?₃·CHCl₃and 10 mol%rac-BINAP under mild conditions,affordi ng 1,3-oxazole-2-thione derivatives in high yields?up to 95%?.The zwitterionic?-allyl palladium intermediates formed in situ by decarboxylation of VECs acted as the three-membered synthons.In this transformation,the C-N bond formation was selectively realized over the C-S bond formation.