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Palladium-Catalyzed Cyclization Reactions of 2-Vinylthiiranes with Heterocumulenes. Regioselective and Enantioselective Formation of Thiazolidine, Oxathiolane, and Dithiolane Derivatives

2001; American Chemical Society; Volume: 66; Issue: 10 Linguagem: Inglês

10.1021/jo010037h

1520-6904

Chitchamai Larksarp, Odile Sellier, Howard Alper,

Catalytic C–H Functionalization Methods

The first palladium-catalyzed ring-expansion reaction of 2-vinylthiiranes with heterocumulenes to form sulfur-containing five-membered-ring heterocycles is described. This regioselective reaction requires 5 mol % of Pd2(dba)3·CHCl3 and 10 mol % of bidendate phosphine ligand (dppp, BINAP), at 50−80 °C, in THF. The reaction of 2-vinylthiiranes with carbodiimides, isocyanates, and ketenimines affords 1,3-thiazolidine derivatives, whereas the reaction with diphenylketene or isothiocyanates results in the formation of 1,3-oxathiolane or 1,3-dithiolane compounds in good to excellent isolated yields and in up to 78% ee.