A Simple, Chirogenic, Enantioselective Synthesis of Chlorins and Isobacteriochlorins

Geminal dialkylated hydroporphyrins are important as intermediates of the vitamin B12 biosynthesis or as cofactors of reducing enzymes in bacteria and plants. They can be synthesized enantioselectively by asymmetric reduction of acylporphyrins and amide acetal Claisen rearrangement with transfer of chirality, and can form complexes like 1 with metals.