Oxidative reactions of azines. 1. Ketohydroxylation of 4-phenyl-1,2,5,6-tetrahydropyridines. Synthesis and structure of 3,4-dihydroxy-4-phenylpiperidin-2-ones and their acetoxy derivatives

N-Alkyl substituted 4-phenyl-1,2,5,6-tetrahydropyridines which do not undergo Wagner hydroxylation are converted in good yields to the corresponding 3,4-dihydroxy-2-oxo-pipendines under modified conditions for this reaction. The molecular structures of a 3,4-dihydroxy-4-phenyl-pipendin-2-one and its diacetatate have been studied by x-ray crystalographic analysis. ©1996 Plenum Publishing Corporation.