A new and efficient method for the synthesis of isoquinoline-3-carboxylate

An isoquinoline-3-carboxylate compound 3 was obtained with a moderate yield of 40% when N-acetyl-(3'-hydroxy-4'-methoxy-5'-methyl)phenylalanine methyl ester 1 was refluxed in HMTA/TFA. However, the anticipated product N-acetyl-(3'-hydroxy-4'-rnethoxy-5'-methyl-6'-formyl)phenylalanine methyl ester 2 could not be found. The possible mechanism was discussed in this article.