Synthesis Of α-nitro Ketoximes From Styrenes And Tert-butyl Nitrite

The synthesis of nitro-substituted aromatic compounds are one of the most developed compounds.According to statistics, more than a third in millions of all kinds of organic compounds known to people are nitro-substituted aromatic compounds. There is no doubt that they play a very important role and with high added value in chemical synthesis. And they are widely used in pesticides, pharmaceuticals, spices, dyes, food additives, rubber chemicals, synthetic materials and other industries. So oximes, as an important part of nitro-substituted compounds, capture the chemists’ attention because they are important in building complex carbon-carbon bonds and carbon-heteratom bonds. However, what had reported previously for synthesis of nitro-substituted aromatic compounds need strict experiment conditions. Its reaction usually employed strong acidic condition, or required the participation of transition metals, which caused certain pollution to the environment inevitably, thus the development was limited. Now we developed a new way to synthesize α-nitro keoximes in a mild condition with s imple operation and it was more friendly to environment. The paper described that under suitable reaction conditions, styrenes can react with tert-butyl nitrite to give α-nitro keoximes as the major product. We found that the use of a mixture solvent of DMSO and water was critical for the success of the reaction. The reaction was found to tolerate a variety of functional groups including electron withdrawing and electron donating groups on the phenyl ring of styrene. For the synthesis of some keoximes we provided a new method and the main content included the following several aspects:Firstly, the author summarized the recent development of the reactions of nitro-substituted compounds, especially oximes.Secondly, while examining the various reaction conditions including water dosage, reaction temperature, and so on. The author found a relatively optimized reaction conditions for synthesis of α-nitro keoximes, which can be established as: 1 equiv of styrene, 2 equiv of tert-butyl nitrite, 1m L DMSO and 0.5 m L water as solvent at room temperature for 12 h in the air.Thirdly, with the optimized protocol in hand, we next turned our attention to explore the scope of the reaction. Starting from diversely substituted styr enes, including electron-withdrawing and electron-donating groups, a series of α-nitro ketoximes were synthesized in good yields. Through analyzing, we learned that the products were Z/E mixtures, and we got different Z/E ratios from different styrenes in reacions. Moreover, we put forward some reasonable analysis accordi ng to the phenomenon in the reaction. In the end, based on literature and working achievements in our laboratory, a possible mechanism was proposed to explain the reaction.