Synthesis of 4H-furo[3,2-b]indole derivatives. III. Preparation of 4H-furo[3,2-b]indole-2-carboxylic acid derivatives

Methyl or ethyl 4H-furo3,2-b]indole-2-carboxylates (Va,b) were prepared from deoxygenation of methyl or ethyl 5-(2-nitrophenyl)-2-furoates (IIIa,b) and thermolysis of methyl or ethyl 5-(2-azidophenyl)-2-furoates (VIIIa,b). 4H-Furo3,2-b]indole-2-carboxylic acid amides (XIa-h) were obtained by the reaction of 4H-furo3,2-b]indole-2-carboxyl chloride (X) with the appropriate amines.