Reactions of 3-methyl-2-oxopyrazolidinium ylides with phenylsulfonylacrylonitriles

A series of methyl oxopyrazolidinium ylides was reacted with (E)-3-(2-hydroxyphenyl)-2-(phenyl-sulfonyl)acrylonitrile and 2-phenylsulfonyl acrylonitrile to give rise to (1R,2S,3S)-5-methyl-7-oxo-1,3-p-substituteddiphenyl-2-(phenylsulfonyl)-hexahydropyrazolo[1,2-a]pyrazole-2-carbonitriles through a sequential reaction accompanying methyl pyrazolone and o-quinone methide releases possibly instead of an anticipated cycloaddition process and 1,3-dipolar cycloaddition route. All the new products were identified by means of spectral/physical characteristics including X-ray diffraction data and HRMS measurements. In addition, a plausible mechanism is proposed for hydroxyphenyl substituted acrylonitrile case. (C) 2015 Elsevier Ltd. All rights reserved.