SIMPLE SYNTHETIC MODELS OF CYTOCHROME-P-450 - EFFICIENT CATALYSTS IN HYDROCARBON OXIDATIONS

Metalloporphyrin-catalysed hydrocarbon oxidation is a particularly int eresting topic both to understand the transient intermediates involved in the catalytic cycle of natural cytochrome P-450 mono-oxygenases an d to stimulate the search of new, efficient and selective oxidation ca talysts to be used for preparative purposes. The aim of this review is to highlight the efforts of chemists in mimicking cytochrome P-450 en zymes by means of synthetic models, with the final goal of selectively oxidising hydrocarbons on a preparative scale, under mild conditions, using cheap, easy-to-handle and clean oxygen sources. The features of cytochrome P-450, the synthesis of tetraarylporphyrins and the cataly tic systems used as models of natural enzymes are briefly surveyed in the first part of this article. The second part covers the use of simp le <<self-consistent>> models and of chiral porphyrins capable of ster eoselective hydrocarbon oxidation. The main problems considered are th e chemical stability and the efficiency (overall turnover numbers) of the catalytic systems.