Efficient, Catalytic and Oxidative Deoximation of Aldoximes and Ketoximes by Ferric Nitrate and Catalytic Amounts of Bromide Ion

Finding molecules which are able to catalyze the reaction between others is an important contribution of molecular chemists to increase the efficiency of chemical reactions whereby our daily life based on consumption of chemicals is shifted closer to an ecologically and economically tolerable equilibrium with our environment. The development of heterogeneous catalysts for fine chemicals synthesis has become a major area of research. Also important aspect of clean technology is the use of environmentally friendly catalysts. Development of efficient and new catalytic systems for various organic transformations is an active research area with the aim to develop milder reaction conditions. Carbonyl compounds occupy a central position in organic syntheses. Oximes are easily prepared and highly stable compounds. They are extensively used for protection, characterization and purification of carbonyl compounds. Since oximes can be prepared from non-carbonyl compounds, the regeneration of carbonyl compounds from oximes provides an alternative method for the preparation of aldehyde and ketones. Despite of protecting role of oximes, also they are valuable intermediates in the preparation of nitriles and amides. Although a number of methods for deoximation reaction have emerged in the recent years there is still a scope for newer reagents, because the existing oxidative methods suffer from some disadvantages like long reaction time, difficulties in isolation of products, and formation of overoxidation products leading to low yields. As part of our continuous effort devoted to catalytic reactions, we have been engaged in the development of a new catalytic media based on in situ generation of Br for the selective regeneration of carbonyl compounds from aldoximes and ketoximes. In this article, we report a novel heterogeneous catalytic protocol for the effective regeneration of carbonyl compounds from oximes using ferric nitrate in the presence of catalytic amounts of NaBr and/or KBr. Various aldoximes and ketoximes 1 were deoximated with combination of Fe(NO3)3·9H2O I and catalytic amounts of NaBr II or KBr III (Scheme 1) in dichloromethane at room temperature. The reaction proceeds efficiently in good yields, and the results are summarized in Table 1.