Synthesis of Methyl 2-Isocyano-3-[3 (1H)-indolyl] acrylate and Related Compounds from 3-(Aminomethylene)-3H-indoles

Abstract

Methyl 2-isocyano-3-[3 (1H)-indolyl] acrylate (1) was synthesized in 73-75% yield by the reaction of 3-(aminomethylene)-3H-indoles (5) with methyl α-isocyanoacetate (3) in pyridine or dimethylformamide, while the reaction in methanol afforded selectively 2-(aminomethyleneamino)-3-[3 (1H)-indolyl] acrylates (6a-e) in 63-100% yields. The mechanisms of formation of 1 and 6 are discussed. Both 1 and 6a-e were hydrolyzed to N-formyl-α, β-dehydrotryptophan (8) and/or its methyl ester (2).