Oxidation reactions of azines. 4. Conjugation of 4-aryl-1,2,5,6-tetrahydropyridines with compounds containing an activated methyl group. Synthesis and structure of 2-acylmethylene- and 2-nitromethylene-1,2,5,6-tetrahydropyridines

A novel Csp 3-Csp 3 oxidative conjugation with compounds containing an activated methylene group has been described in the case of 1-alkyl-4-aryl-1,2,5,6-tetrahydropyridines. It was shown that treatment of the indicated Δ3-piperidines with methyl ketones or nitromethane in the presence of KMnO4 gives their 2-acylmethylene- or 2-nitromethylene derivatives respectively. ©1997 Plenum Publishing Corporation.