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‐furo[3,2‐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‐Furo[3,2‐b]indole‐2‐carboxylic acid amides (XIa‐h) were obtained by the reaction of 4H‐furo[3,2‐b]indole‐2‐carboxyl chloride (X) with the appropriate amines.