Synthesis of some 9-aminoacridines with bulky substituents

Abstract

2-s-Butyl-, 2-t-butyl-, and 2,7-di-t-butyl-9-aminoacridine, and other acridines, have been synthesised from the corresponding 2-carboxydiphenylamines (diphenylamine-2-carboxylic acids). Their ¹H n.m.r. spectra have shown that earlier assignments made for 9-aminoacridine must be revised. The n.m.r. spectra for intermediates in the syntheses show a steric effect for the t-butyl group and indicate the presence of geometric and rotational isomers of the sterically hindered benzimidates, which were rearranged to give the carboxydiphenylamin derivatives. The t-butyl group was eliminated in all attempts to prepare 9-t-butylaminoacridine. Acridine 9-aminoacridine, and a number of other derivatives could not be alkyalted at position 10 by a variety of large alkylating agents because preferential elimination took place.