Intramolecular cyclization of 15-carboxy-13-amide derivatives of chlorin e6 under the action of 2-Chloro-1-methylpyridinium iodide

Abstract

We have shown the possibility of intramolecular cyclization with the participation of the carboxyl group at position 15 of the chlorin macrocycle with a primary or secondary amide group at position 13 through the formation of an imide bond under the action of 2-Chloro-1-methylpyridinium iodide; the imide bond can be used to form a seven-membered exocycle. Using this reaction, we synthesized a number of cycloimide derivatives of chlorophyll a. The proposed synthetic route can be carried out if the substituent at the amide nitrogen atom has a hydroxyl, dimethylaminomethyl or vinyl group, which opens up possibilities for further chemical modification of the obtained derivatives.