Opening of forbinexocycle by weak O-nucleophiles. Study and optimisation of free chlorine e6 synthesis methods

Abstract

The article considers issues concerning the reaction of exocycle opening in phorbin molecules (on the example of methylpheophorbide a) under the O nucleophiles - water and alcohols action. According to the author, under certain conditions relatively weak nucleophiles as water and alcohols can cause the opening of the exocycle in the molecule of methylpheophorbide a with the formation of chlorine derivatives e6. The study of this reaction, in addition, reveals new synthetic methods to obtain chlorine e6 esters of different degrees of substitution, and eventually - free chlorine e6 in the form of triacids. Free chlorine is a valuable photosensitiser for photodynamic therapy (PDT), and a starting compound for the preparation of other photosensitizers. The article also discusses possible synthetic approaches to obtain free chlorine e6.