Synthesis of tetraphenylporphyrin molecules containing heteroatoms other than nitrogen. Part 4. Symmetrically and unsymmetrically substituted tetraphenyl-21,23-dithiaporphyrins

The synthesis of symmetrically as well as unsymmetrically substituted tetraphenyl-21,23-dithiaporphyrins (S₂TPP) is described. The reaction of 2,5-dilithiothiophen with substituted benzaldehydes is used for the preparation of substituted 2,5-bis(phenylhydroxymethyl)thiophens. Symmetrically substituted S₂TPP molecules result from reaction of these dialcohols with equimolar quantities of pyrrole. Unsymmetrically substituted S ₂TPP molecules are obtained by first reacting one diol with an excess of pyrrole and subsequently reacting the intermediate obtained with another diol. The compounds prepared are the tetrakis-(p-methoxyphenyl)-, tetrakis-(p-chlorophenyl)-, tetrakis-(p-fluorophenyl), α,β-bis-(p- methoxyphenyl)-γ,δ-diphenyl-, α,β-bis-(p-fluorophenyl)- γ,δ,diphenyl-,α,β-bis-(p-chlorophenyl)-y, S-bis-(p-methoxyphenyl)-.anda,ß-bis-(p-fluorophenyl)-y, 8-bis-(p-methoxyphenyl)-por-phyrins. The optical and ¹H n.m.r. (270 MHz) spectra of these porphyrins are presented.