Preparation of 3-(3,4,5,6,-tetrahydrophthalimido)-benzaldehydes

Abstract From the Canadian patent

3-(3,4,5,6-Tetrahydrophthalimido)-benzaldehydes of the type I, (see fig. I) or corresponding derivatives substituted in the phenyl ring are prepared by, a) acetalization of a 3-nitrobenzaldehyde III or of a corresponding derivative with an alcohol IV in the presence of an acidic catalyst to give the corresponding cyclic acetal V, (see fig II) b) reduction of the cyclic acetal V with hydrogen to give the corresponding amino compound II and c) subsequent condensation of this aminophenyl acetal II with 3,4,5,6-tetrahydrophthalic anhydride in an acidic reaction medium.