Synthesis and spectral and structural characterization of a new series of bis-strapped chiral porphyrins derived from L-proline

New chiral porphyrins were obtained in reasonable yields in three steps, st arting from the alpha beta alpha beta atropisomer of meso-tetrakis(o-aminop henyl)porphyrin (TAPP). These potential catalysts for the enantioselective epoxidation of alkenes were obtained by the reaction of different linkers o n the same L-prolinoyl-picket porphyrin. Their H-1 NMR spectral characteris tics, as well as the crystal structure of one of them, clearly indicate tha t the orientation of the proline cycle depends on the linker used to tether the two pickets on each side of the porphyrin, The same linker is employed for both sides of the porphyrin; hence the resulting D-2-symmetric superst ructure.