Co(III)-Porphyrin-Mediated Highly Regioselective Ring-Opening of Terminal Epoxides with Alcohols and Phenols

Co-T(p-OMe)PP-SbF6 (1-SbF6, T(p-OMe)PP = 5,10,15,20-tetrakis(4-methoxyphenyl)porphyrinato) is demonstrated to be a highly active and regioselective catalyst in the ring-opening of various epoxides with alcohols and phenols. 1-SbF6 is demonstrated to be twice as active as the established Co-salen-SbF6 (2-SbF6, salen = trans-N,N-bis(3,5-ditertbutylsalicylidene)-1,2-cyclohexanediamine) catalyst, exhibiting >99% regioselectivity in many cases. The catalyst is suggested to promote the ring-opening via a cooperative bimolecular mechanism because the Co-porphyrin dimer, 1d-OTs, is significantly more active compared with the monomeric catalyst, 1-OTs.