Amidation of the ester group of methylpheoforbide a with sterically nonhindered primary and secondary aliphatic amines

Abstract

It is shown that the reaction of methylpheoforbide a with a series of primary and secondary aliphatic amines at elevated temperature (boiling in toluene) leads to the amidation of carbomethoxy group in the position 13(2) of the methylpheoforbide a exocycle instead of the cleavage of exocycle with the formation of the corresponding 13-amides of the chlorin e6. Possible reasons of the observed change in the reaction pathway are presented.