A Simple Route to Prepare Monofunctionalised 21‐Thia‐, 21,23‐Dithia‐, and 21‐Thia‐23‐oxaporphyrins from Unsymmetrical Thiophene Diols and Their Use in the Synthesis of Covalently Linked Unsymmetrical Porphyrin Dimers

Abstract

AbstractA series of unsymmetrical thiophene diols has been prepared in two steps from thiophene in 16–46 % yields. The unsymmetrical thiophene diols containing functionalised aryl groups were then used as key synthons for the synthesis of a series of monofunctionalised 21‐thia (N3S), 21,23‐dithia (N2S2) and 21‐thia‐23‐oxaporphyrins (N2SO). Condensation of one equivalent of unsymmetrical diol with either two equivalents of aldehyde and three equivalents of pyrrole, one equivalent of symmetrical 16‐thiatripyrrane or one equivalent of symmetrical 16‐oxatripyrrane under standard porphyrin‐forming conditions resulted in monofunctionalised 21‐thia‐, 21,23‐dithia‐ or 21‐thia‐23‐oxaporphyrins in decent yields. This unsymmetrical diol method is simple, versatile and gives an access for the first time to any desired monofunctionalised porphyrins with N3S, N2S2 and N2SO porphyrin cores. The use of monofunctionalised N3S, N2S2 and N2SO porphyrins is further demonstrated by synthesising the first examples of three new covalently linked diarylethyne‐bridged unsymmetrical dimers containing two different porphyrin cores such as N2S2‐N4, N2S2‐N3S and N2S2‐N2SO. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)