Tetra-crowned porphyrin as P450 biomimetic model for carbamazepine oxidation

Juvenal C.S Filho,Tatiana C.O Mac Leod,Marilda Das Dores Assis,Maria Carolina A.F Gotardo,John Arthur Joule

doi:10.3998/ark.5550190.0011.511

Juvenal C.S Filho, Tatiana C.O Mac Leod + Show 3 more

Open Access

https://doi.org/10.3998/ark.5550190.0011.511

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Abstract

A substituted porphyrin bearing four crown ether units, H(2)(TCP), was synthesized from the reaction between (5,10,15,20-tetra(o-aminophenyl) porphyrin) and the acyl derivative of the ether (4-carboxy-18-crown-6). The free-base porphyrin was characterized by C, N, and H elemental analysis; UV-vis and IR spectroscopies; and (1)H NMR. The corresponding ironporphyrin, Fe(TCP)Cl, was obtained via iron insertion into H(2)(TCP). Fe(TCP)Cl was employed as catalyst for carbamazepine (CBZ) oxidation by iodosylbenzene (PhIO), 3-chloroperoxybenzoic acid (m-CPBA) or sodium hypochlorite (NaOCl), in methanol or in a biphasic water/dichloroethane system. The crowned ironporphyrin proved to be a highly efficient and selective catalyst for CBZ epoxidation even in the biphasic dichloroethane /H(2)O system, with no need for an additional phase transfer agent.

Highlights

There has been considerable research interest in the synthesis of porphyrins with various substitutents in view of their ability to function as models that mimic several biofunctions such as heme oxygenation and cytochrome activity.[1]
The crown ether units bind to the porphyrin through four points, namely the ortho position of the phenyl rings, and they remain close to the central cavity of the porphyrin
The binding of four crown ether units to the porphyrin did not lead to significant changes in the energy of the orbitals involved in the porphyrin electronic transitions

Summary

Introduction

There has been considerable research interest in the synthesis of porphyrins with various substitutents in view of their ability to function as models that mimic several biofunctions such as heme oxygenation and cytochrome activity.[1]. This orientation, coupled with the steric effect imposed by the presence of the ether, may result in high selectivity for the catalytic reaction.[11] When two or more crown ether units are located on the same side of the porphyrin plane, they can act as clamps that orient and direct the substrate toward the cavity of the active site.[12] The presence of a polyether attached to a porphyrin may aid solubilization of the water-soluble oxidant and/or substrate in the organic medium, avoiding the need for a phase transfer agent.[13]

Results

Conclusion