Biphilic Organophosphorus Catalysis: Regioselective Reductive Transposition of Allylic Bromides via PIII/PVRedox Cycling
摘要:
We report that a regioselective reductive transposition of primary allylic bromides is catalyzed by a biphilic organophosphorus (phosphetane) catalyst. Spectroscopic, evidence supports the formation of a penta:coordinate (sigma(5)-P) hydridophosphorane as a key reactive intermediate. Kinetics experiments and computational modeling are consistent with a unimolecular docomposition of the sigma(5)-P hydridophosphorane via a conceited cyclic transition,structure that delivers the observed allylic transposition and completes a novel P-III/P-V redox Catalytic cycle. These results broaden the growing repertoire., of reactions catalyzed within the P-III/P-V redox couple and suggest additional opportunities for organophosphorus,catalysis in a biphilic mode.
Further ring openings and ring expansions of phosphetans
作者:J. R. Corfield、M. J. P. Harger、J. R. Shutt、S. Trippett
DOI:10.1039/j39700001855
日期:——
4-hexamethyl-1-phenylphosphetanium iodide led to ring opening via pentacovalentintermediates as also did the action of cyanide ion on this salt. Ring expansions of 2,2,3-trimethyl- and 2,2,3,3-tetramethyl-1-phenylphosphetan on reaction with ethyl propiolate in wet ether, on reaction with dimethyl acetylenedicarboxylate, and on hydrolysis of the iodomethylphosphetanium salts, occur with migration of the