The First Examples of Unsymmetrically Substituted Anhydro Dimers of Salicylaldehyde

Abstract

Three new nitro-substituted anhydro dimers of salicylaldehyde have been obtained, either by selective nitration of the parent dimer or by statistical dimerization of 3- and 5-nitrosalicylaldehydes. These constitute the first examples of dimers without identical substitution in the two rings and therefore without a C₂ axis.