Synthetic studies in the field of chlorobium chlorophyll

By the condensation of α-halogenomethyl derivatives of pyrroles with α-unsubstituted pyrroles the synthesis of the following unsymmetrical dipyrrolylmethanes has been effected: 5-benzyloxycarbonyl-5′-ethoxycarbonyl-3, 3′-di(β-methoxycarbonylethyl)-4,4′-dimethyl-2,2′-dipyrrolylmethane (IIIa), 5-benzyloxycarbonyl-5′-ethoxycarbonyl-3-(β-methoxycarbonylethyl)-4, 4′-diniethyl-3′-n-propyl-2,2′-dipyrrolylmethane(IIIb), 3-acetyl-5-benzyloxycarbonyl-4′-ethyl-5′-methoxycarbonyl-3′, 4-dimethyl-2,2′-dipyrrolylmethane (IIIc), and 3-bromo-5-benzyloxycarbonyl-4′-ethyl-5′-methoxycarbonyl-3′, 4-dimethyl-2,2′-dipyrrolylmethane (IIId). Hydrogenation of the unsymmetrical dipyrrolylmethanes IIIa, b, c, and d has given the corresponding monocarboxylic acids IVa, b, c, and d. The formylation of the dipyrrolylmethanemonocarboxylic acid IVa has given 5′-ethoxycarbonyl-5-formyl-3,3′-di(β-methoxycarbonylethyl)-4, 4′-dimethyl-2,2′-dipyrrolylmethane (V).