Sapphyrins, derivatives and syntheses
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The present invention involves, in addition to many unique substituted sapphyrins, a novel method for synthesizing sapphyrins with good efficiency and high yield. An improved 9-step synthesis of substituted sapphyrins, e.g., the two C.sub.2 symmetric sapphyrins, compounds 2 and 4 of FIG. 1C, is described herein. This synthesis involves as an important step the condensation between a tripyrrane diacid and a diformyl bipyrrole. The key tripyrrane component is prepared in three high-yield steps from readily available pyrrolic precursors and the bipyrrole portion is prepared in four steps from ethyl 3-methyl-4-methylpyrrole-2-carboxylate in roughly 33% yield overall.