Selective and Efficient Oxidation of Benzyl alcohols to Benzaldehydes by Polydoxirane in the Presence of Molecular Oxygen at Room Temperature

Abstract

Oxidation of alcohols that lead to the preparation of carbonyl compounds are an important class in organic synthesis due to their applications in production of various pharmaceutical and chemical materials [1]. Various protocols and attempts to oxidation of alcohols (primary and secondary) in order to form carbonyl compounds show the importance of this basic reaction in organic synthesis [2]. However, there is a continuous demand to develop synthetic methods for discriminating efficiently various functional groups, because most of the reported methods suffer from lack of selectivity, using toxic solvents and oxidant, tedious work-up and harsh condition. In this point of view, chemoselective methods allow the oxidation of primary alcohols without the exhorting of competitive secondary alcohols. Salicylaldehyde is one of the safe, readily available organic compounds in health and reactivity point of view, which can be extracted from natural sources such as buckwheat [3]. In this work, we used an efficient and selective method for oxidation of a variety of benzyl alcohols to the corresponding benzaldehydes in the presence of polydioxirane (PDOX) by molecular oxygen at room temperature (Fig. 1). PDOX was prepared by polycondensation reaction of 5-chloromethyl salicylaldehyde followed by decoration of dioxirane groups of the framework of PDOX. In our previous work we have demonstrated the ability of the PDOX over selective epoxidation of olefins at room temperature as efficient alternative to dimethyldioxirane.