Ag-Catalyzed or Ag/PPh3-Catalyzed Chemoselective Switchable Cascade Reactions of N-Propargyl Thiocarbamoyl Fluorides and Malonate Esters

摘要

The divergent chemoselective synthesis of 2-methylene-2,3-dihydrothiazoles and 4-benzylidene pyrrolidine-2-thiones (most with E stereoselectivity) from N-propargyl thiocarbamoyl fluorides and malonate esters in moderate to excellent yields with a broad substrate scope and functional group tolerance has been accomplished. AgNTf2 catalyst at 60 degrees C in dichloroethane provided 4-benzylidene pyrrolidine-2-thiones. AgOTf catalyst and PPh3 ligand in refluxing acetonitrile resulted in a complete switch in the reactivity of formed alpha,alpha-diester thioamide intermediates followed by isomerization to access 2-methylene-2,3-dihydrothiazoles.

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