[2.2]-para-cyclophane-4-carbaldehyde as building-block for chiral ligands - Part II: Epoxidation of alkenes catalyzed by the Mn(III)-complex of an atropoisomerically pure (alpha,beta,alpha,beta)-tetraarylporphyrin

The synthesis of the Mn(III)-complex of the new enantiopure, atropoisomerically pure chiral porphyrin (alpha,beta,alpha,beta)-1 is described. The compound was used as the catalyst in the epoxidation of unfunctionalized olefins using aqueous NaOCl, 30%-H2O2 or PhIO as oxygen donors. Up to 780 overall turnovers were obtained in the presence of NaOCl and PhIO, whereas with 30%-H2O2 only catalase activity was observed. Contrary to expectations based on previous results [S. Banfi, A. Manfredi, F. Montanari, G. Pozzi, S. Quici, J. Mel. Catal., 113 (1996) 77], only racemic epoxides were obtained.