Synthesis of D-2-symmetric 5,10,15,20-tetraarylporphyrins from C-2-symmetric benzaldehydes and achiral aryldipyrromethanes

A series of new enantiomerically pure D-2-symmetric 5,10,15,20-tetraarylporphyrins has been synthesized by condensation of C-2-symmetric substiuted benzaldehydes with achiral aryldipyrromethanes in 22-40% yield. The mild conditions used enable selective incorporation of the chiral arenes at the 5,15-positions and the achiral arenes at the 10,20-positions. Due to the incorporation of the C-2-symmetric chiral arenes, no atropisomers are possible in these D-2-symmetric ligands. Manganse complexes of these ligands are catalysts for the enantioselective epoxidation of cis-beta-methylstyrene. Copyright (C) 1996 Elsevier Science Ltd