EXPEDITIOUS SYNTHESIS OF DIHYDROBENZO-[2,1-B-3,4-B-']-, [1,2-B-5,4-B'], AND [1,2-B-4,5-B-']-DIPYRROLES

A simple, high-yield, two-step synthesis of the title compounds (1)-(3) is described, based on the catalytic reduction of the bis-enamines (4)-(6), in turn obtained by condensation of dimethylformamide diethyl acetal with the appropriate dinitro-xylene.