The Catalytic Oxidation Synthesis Of Isoxazoline Using Aldehyde Or Aldehyde Oxime As Materials

Isoxazoles and isoxazolines are two major classes of five-membered nitrogen containing heterocycles, and they are very important organic synthetic intermediates. These two kinds of structure widely exist in natural compounds and drugs, many of them have significant biological activity and high medicinal value. However, the present synthetic procedures have some disadvantages such as hard to get the starting materials, operation is too complex and some chemicals are environmentally harmful. This paper introduces some simpler, more economic and environmentally friendly procedures for the synthesis of isoxazolines. This paper consists of three chapters, the contents are as follows:1. Literature review. The application of isoxazolines in medicine, pesticide fields and in organic synthesis as synthons is first introduced. The development and application of metal free catalytic oxidation reaction in organic synthesis is then reviewed. Some of the traditional isoxazoline synthetic methods are summarized and analyzed.2. The one-pot synthesis of isoxazoline catalyzed by hypervalent iodine compound. This chapter briefly introduces the hypervalent iodine reagents and their applications. Using aldehydes, hydroxyamine and alkenes as materials, a convenient one-pot, three-step procedure for the synthesis of isoxazolines has been developed, in which iodobenzene is used as the catalyst for the in situ generation of a hypervalent iodine intermediate. This new method is simper and more economical compared with the reported methods, when using aromatic aldehydes as substrates,the yields were between 49%-94%.3. Hypohalous acid mediated the oxidation of aldehyde oxime for the synthesis of isoxazoline. Because hypohalous acid can oxide the aldehyde oxime into nitrile oxide, which then reacts with the unsaturated hydrocarbons to form isoxazol(in)es. We have tested differfent halide as the precusor of hypohalous acid to mediate the oxidation of aldehyde oxime. On the base, we select KCl and 1-iodopropane combined with the "green oxidant" Oxone as the catalytic oxidative system to oxide aldehyde oxime and finally isoxazolines are synthesized, which provides a more environmentally friendly and efficient procedure for the synthesis of isoxazolines. When the reaction was mediated by potassium chloride, most yields were between 73%-98%.