Synthesis of isotopically labeled zinc methyl bacteriopheophorbide-d as a model for light-harvesting antenna pigments

Grignard reaction of methyl pyropheophorbide-d (1) possessing a 3-formyl group with methyl magnesium iodide selectively gave methyl bacteriopheophorbide-d (2) possessing a 3-(1-hydroxyethyl) group. When 13CH3MgI and CD3MgI were used as the Grignard reagents, specifically labeled 2 were afforded, of which zinc complexes 3 serve as model compounds for natural bacteriochlorophylls-d.