Derivatives of Furo[3,2-b]pyrrole

A number of methyl 2-substituted, 2,3-disubstituted-4H-furo[3,2-b]pyrrole-5-carboxylates (V - VII) and methyl 1H-benzo[b]furo[3,2-b]pyrrole-2-carboxylate (VIII) was prepared by the thermolysis of corresponding methyl 2-azido-3-(R1,R2-substituted-2-furyl)propenoates (I - IV). N-Methyl and N-benzyl derivatives IX - XVI were prepared at the phase-transfer catalysis conditions. Hydrolysis of some N-methyl and N-benzyl substituted esters furnished corresponding acids XVII - XXII. The hydrazides XXIII - XXX were obtained from corresponding esters and hydrazine hydrate. The preparation of 1-benzylbenzo[b]furo[3,2-b]pyrrole (XXXI) is described as well.