Alphabet soup within a porphyrinoid cavity: synthesis of heterocarbaporphyrins with CNNO, CNOO, CNSO and CNSeO Cores from an oxacarbatripyrrin

The first examples of porphyrin analogues with four different core atoms have been synthesized from an oxacarbatripyrrin intermediate. Acid-catalyzed condensation of the tripyrrin analogue with pyrrole or furan dialdehydes gave 22-oxa- and 22,23-dioxacarbaporphyrins, while reactions with furan, thiophene or selenophene dicarbinols afforded diphenyl dioxa-, oxathia- and oxaselenacarbaporphyrins.