| abstract |
A process for the preparation of pyropheophorbide a and its derivatives, including 3-devinyl-3-(1'-hexyloxy)ethyl-pyropheophorbide-a, otherwise known as HPPH, is provided. The process involves treating chlorin e6, in the form of its trimethyl ester, with a base, followed by heating to give pyropheophorbide a, which is converted to HPPH by treatment with acid, followed by hexyl alcohol under basic conditions. |