25,27-dithiasapphyrin and pyrrole-inverted isomer of 21,23-dithiaporphyrin from condensation of pyrrole and 2,5-bis(p-tolylhydroxymethyl)thiophene

[GRAPHICS] A novel aromatic isomer of 5,10,15,20-tetra(p-tolyl)-21,23-dithiaporphyrin (S2TTP) with an inverted pyrrole ring, 5,10,15,20-tetra(p-tolyl)-2-aza-21-carba-22,24-dithiaporphyrin (S2CTTP), and 5,10,15,20-tetra(p-tolyl)-25,27-dithiasapphyrin (25,27-S2TTSH), have been obtained by a condensation of 2,5-bis((p-tolyl)hydroxymethyl)thiophene and pyrrole, A conformational equilibrium, unique in a sapphyrin class, between two S(27)-thiophene-flipped and planar structures of neutral 25,27-S2TTSH was detected by H-1 NMR.