From porphyrin benzylphosphoramidate conjugates to the catalytic hydrogenation of 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin

Marcos C de Souza; Leandro F Pedrosa; Géssica S Cazagrande; Vitor F Ferreira; Maria G P M S Neves; José A S Cavaleiro

doi:10.3762/bjoc.10.54

From porphyrin benzylphosphoramidate conjugates to the catalytic hydrogenation of 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin

Beilstein J Org Chem. 2014 Mar 10:10:628-33. doi: 10.3762/bjoc.10.54. eCollection 2014.

Authors

Marcos C de Souza¹, Leandro F Pedrosa², Géssica S Cazagrande², Vitor F Ferreira², Maria G P M S Neves³, José A S Cavaleiro³

Affiliations

¹ Departamento de Química Orgânica, Universidade Federal Fluminense, 24020-141 Niterói, RJ, Brasil, ; Department of Chemistry & QOPNA, University of Aveiro, 3810-193 Aveiro, Portugal.
² Departamento de Química Orgânica, Universidade Federal Fluminense, 24020-141 Niterói, RJ, Brasil.
³ Department of Chemistry & QOPNA, University of Aveiro, 3810-193 Aveiro, Portugal.

Abstract

Three new porphyrin aminoalkyl dibenzylphosphoramidates were synthesized by nucleophilic aromatic substitution of one p-fluorine atom of 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin (TPPF 20 ) by primary aminoalkyl dibenzylphosphoramidates. The nucleophilic aromatic substitution was promoted by microwave irradiation in N-methyl-2-pyrrolidinone. Attempts to remove the benzyl groups of the phosphoramidate moiety by hydrogenolysis with 10% Pd/C led to the cleavage of the P-N bond and the reduction of the macrocycle to hydroporphyrin-type derivatives. The extent of the effect of the catalytic hydrogenation to TPPF 20 with 10% Pd/C was then studied with a variety of solvents. The results showed that ethanol/DMF is the solvent of choice to produce chlorin TPCF 20 and an ethanol/DMF/NEt3 mixture is more adequate to produce isobacteriochlorin (TPIF 20 ).

Keywords: catalytic hydrogenation; chlorin; isobacteriochlorin; phosphoramidate; porphyrin.