Larksarp C, Sellier O, Alper H. Palladium-Catalyzed Cyclization Reactions of 2-Vinylthiiranes with Heterocumulenes. Regioselective and Enantioselective Formation of Thiazolidine, Oxathiolane, and Dithiolane Derivatives.
J Org Chem 2001;
66:3502-6. [PMID:
11348136 DOI:
10.1021/jo010037h]
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Abstract
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 Pd(2)(dba)(3).CHCl(3) and 10 mol % of bidendate phosphine ligand (dppp, BINAP), at 50-80 degrees 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.
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