Journal of the American Chemical Society, Vol.132, No.48, 17282-17295, 2010
Polarization of the Pyridine Ring: Highly Functionalized Piperidines from Tungsten-Pyridine Complex
The N-acetylpyridinium complex of {TpW(NO)(PMe3)} undergoes regio- and stereoselective reactions with a broad range of common organic nucleophiles, providing a family of 1,2-dihydropyridine (DHP) complexes of the form TpW(NO)(PMe3)(3,4-eta(2)-DHP). The present study explores the elaboration of these systems into novel piperidines. The addition of an acid to the DHP complexes generates highly asymmetric pi-allyl complexes that in turn react with a second nucleophile at either C3 or C5. The subsequent oxidative decomplexation of these materials yields several piperidinamides with unconventional substitution patterns.