Pyrroles from ketoximes and acetylene. 19. Regioselectivity of the reaction of alkyl benzyl ketoximes with acetylene Academic Article uri icon

abstract

  • Alkyl benzyl ketoximes react with acetylene at 60–150 °C in MOH-dimethyl sulfoxide (M = Li, K) primarily by means of the methylene group of the benzyl grouping, which is primarily anti-oriented with respect to the hydroxy group, to give 2-alkyl-3-phenylpyrroles in greater than 70% yields. The specific participation of the antimethylene group in the construction of a pyrrole ring constitutes evidence against mechanisms that include a [3,3]-sigmatropic shift in O-vinyl oximes. It follows from the results obtained that the reaction proceeds through an anti-dianion of the benzyl type stabilized by conjugation with the aromatic ring.

publication date

  • January 1, 1982