Schiff bases prepared by the reaction of 1-cyclopentyl-1-(3,4-dimethoxyphenyl)methanamine with various benzaldehydes were reduced with sodium borohydride to obtain the corresponding secondary amines. Under the Eschweiler–Clarke reaction conditions, the latter undergo cyclization, yielding substituted N-benzyl-4-spirocyclopentane-6,7-dimethoxytetrahydroisoquinolines. Secondary amines derived from 1-cyclopentyl-1-phenylmethanamine failed to cyclize under the Eschweiler–Clark reaction conditions and transform into N-methyl derivatives. The products containing hydroxyl substituents were isolated as hydrobromides. The synthesized compounds were screened for antioxidant and cardiotonic activities.
Aghekyan et al. (Thu,) studied this question.