15,23-Dihydrosirohydrochlorin 21H,23H-Porphine-2,7,12,18-tetrapropanoic acid, 3,8,13,17-tetrakis(carboxymethyl)-7,8,12,13,20,24-hexahydro-8,13-dimethyl-, (7S-(7alpha,8beta,12alpha,13beta))- 82542-92-5 Precorrin 2