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Ring Expansion and Contraction in Reactions of an Alkyne with Stannylplatinum(IV) Metallacycles: Formation of an Alkyl(alkenyl)(alkynyl)platinum(IV) Complex
journal contribution
posted on 2002-02-16, 00:00 authored by Michael C. Janzen, Hilary A. Jenkins, Michael C. Jennings, Louis M. Rendina, Richard J. PuddephattThe five-membered stannylplatinum(IV) metallacycles [PtMe2{SnMe2ESnMe2E}(bu2bpy)],
E = S, Se, Te, bu2bpy = 4,4‘-di-tert-butyl-2,2‘-bipyridine, undergo facile ring expansion by
insertion of the electrophilic alkyne RCCR, R = CO2Me, into the PtE−Sn bond to yield the
corresponding seven-membered metallacycles [PtMe2{SnMe2ESnMe2CRCRE}(bu2bpy)]. The
seven-membered metallacycles slowly eliminate “Me2SnE” to give new five-membered metallacycles [PtMe2{SnMe2CRCRE}(bu2bpy)]. When E = Se, reaction with excess RCCR gives
the complex [PtMe2(CRCRH)(CCR)(bu2bpy)], which contains alkyl, alkenyl, and alkynyl
functionalities in the same molecule. In the presence of excess RCCR and [(Me2SnSe)3], the
products Se(Z-CRCHR)2 and the selenole Se(CRCRCRCR) are formed catalytically.