Synthesis of heterocycle‐substituted pyropheophorbide derivatives

Abstract

Abstract Methyl pyropheophorbide‐ a (MPPa) ( 1 ) was converted to two aldehydes, methyl 2‐formylmethyl‐2‐devinylpyropheophorbide‐ a ( 2 ) and methyl 2‐formyl‐2‐devinylpyropheophorbide‐ a ( 3 ). The former 2 reacted with active methylene compounds having a cyano function in the presence of sulfur to afford thiophene‐substituted chlorins 5a‐c and reacted with arylhydrazines to yield indole‐substituted chlorins 6a‐d . From the latter 3 , a α‐diketo chlorin 7 was obtained via Wittig reaction and oxidation. Compound 7 reacted with o ‐phenylenediamine to afford 2‐quinoxalyl‐substituted pyropheophorbide‐ a 8. The reaction of MPPa ( 1 ) with anthranilamide to give a spiro‐substituted compound 9 .