Synthesis and epoxide-opening reaction of a 3-oxiranyl-chlorophyll derivative

A chlorophyll derivative possessing an oxiranyl group at the C3-position was synthesized from methyl pyropheophorbide-d bearing the 3-formyl group under Corey–Chaykovsky reaction conditions in a good yield. The ring-opening reaction of the protonated epoxide-moiety with various nucleophiles gave the 31-adducts with high regioselectivity, while the treatment of BF3·Et2O afforded an isomeric 3-(formylmethyl) chlorin as the sole isolable product. The above ring-opening hardly affected their visible absorption spectra to give similar Qy and Soret bands at around 660 and 410 nm, respectively, in dichloromethane.