Useful Synthesis of α,β-Dehydrotryptophan Derivatives

Article abstract of DOI:10.1021/jo00340a020

N-Acyl-α,β-dehydrotryptophan (ΔTrp) esters 4a-h were directly synthesized by the reaction of 3-<(1-pyrrolidinyl)methylene>-3H-indole (2) with N-acylglycinates 3a-h in resonable yields.Of these, N-formyl-substituted ΔTrp methyl ester (4a) was easily converted into ΔTrp methyl ester (7) in a high yield by acidolysis with dry methanol-hydrogen chloride.Furthermore, 7 was successfully used for the preparation of a dipeptide, N-alanyl-substituted ΔTrp methyl ester (10).