In light of the recent interest in the chemistry and synthesis of isobacteriochlorins, we have reinvestigated the photoreduction of zinc (I1) methyl pyropheophorbide a (ZnPPheo, 1) previously reported by Seely.'It has been known for some time that ascorbic acid photoreduction of zinc (I1) phylloerythrin methyl ester with diazabicyclo [2.2. 2] octane (DABCO) as a catalyst gives the thermodynamically least stable cis-pheophorbide ( ...