Synthesis of N-[1-(2-hydroxyphenyl)-2-nitroethyl]benzamides by condensation of α-nitroacetophenones with salicylic aldehydes followed by rearrangement

Abstract

A new rearrangement of Knoevenagel condensation products of salicylic aldehydes with α-nitroacetophenones in the presence of ammonium acetate yielding N-[1-(2-hydroxyphenyl)-2-nitroethyl]benzamides has been described. The transformation occurs via intramolecular cyclization affording a chromane intermediate followed by its ring opening and acyl group transfer. The reaction pathway, the role of the phenolic hydroxy group, as well as applicability and limitations of this method were studied. A number of the target benzamides were obtained in good yields.