Hemisynthesis of 132,173-cyclomesopheophorbide-a-enol

Cyclopheophorbides are often major chlorophyll-a degradation products in biogeochemical situations. Authentic standards are unavailable and facile generation of pure compounds is required. 132,173-Cyclomesopheophorbide-a-enol (mesoCYCLO) was prepared in moderate yields via a known Dieckmann-like condensation of mesopyropheophorbide-a methyl ester (mpPBIDaME). MesoCYCLO was purified by flash chromatography over a polymeric reversed phase (PRP-1™) material, negating the requirement for a crystallization step. Structural verification included ultraviolet-visible spectrometry, high resolution matrix (sulfur/CS2) assisted laser desorption mass spectrometry, and nuclear magnetic resonance.