Novel N(23)-C(10)-linked linear tetrapyrroles

SnCl4-catalyzed condensation of 2,3,7,8-tetramethyl-10(H)-dipyrrinone (3) with acetone gave a good yield of the novel tetrapyrrole 1. Similarly, the tetraethyldipyrrinone (4) gave analog 2, whose structure was proved by X-ray crystallography.