The Research Of Epoxides Ring-Opening Reaction

With the development of the modern organic synthetic chemistry, heterocyclic compounds are of great importance in organic synthesis, especially epoxides, mainly refers to ternary ring ether and its derivatives, whose chemical properties are very lively, and they are one of the important intermediates in the synthesis of drugs. Therefore epoxides play a great important role in the medical, pharmacy and other fields. Epoxides have very strong tension of rings, thus they can easily react with nucleophiles for ring opening to form a variety of products catalyzed by acid or alkali. Therefore, they have a wide range of application. Because of the importance of epoxides in organic synthesis, chemists have been engaged in unremitting exploration and research.First, the synthetic methods of epoxides have been summarized according to the type of reaction. These methods include intramolecular Williamson reaction, Darzens reaction, and olefins peroxide oxidation, etc. Useness of the reaction of carbonyl compounds with sulfonium salt, some epoxides have been prepared in our laboratory. Next, the applications of epoxides in organic synthesis have also been reviewed.β-Hydroperoxy alcohols are a multi-functional group compounds, and have a very lively hydroxy peroxy and hydroxyl groups. They can react with many nucleophilic reagents having electron-deficient groups. These peroxy alcohols not only exist in a wide range of natural products but also have a lot of application in medicine and pharmacology, especially for the synthesis of 1,2,4-trioxanes, which are being actively investigated as antimalarial agents. It has been reported in the literature that cyclic peroxy compounds can produce double-oxygen free radicals through photolysis or pyrolysis, so they can play bactericidal role in medicine and pharmacology. We have developed a novel, mild and highly efficient procedure for the synthesis ofβ-hydroperoxy alcohols. The use of the inexpensive and easily available catalyst, the high yields, relatively short reaction times, together with the potential usefulness of the process for industrial applications, are all attractive features of this method. Most of our compounds were characterized by IR, ¹HNMR and elemental analysis.Indole, pyrrole and its derivatives not only are essential to the heterocyclic compounds, but also are important fine chemical raw material. They are widely used in medicine, pesticides, spices, food feed additives, dyes and other areas. The new application for their research has always been lasting and is continually being developed. In particular, 3-alkyl indole derivatives have significant biological and pharmacological activity. A mild and efficient method has been developed for Friedel-Crafts alkylation of nitrogen heterocycles in the presence of SbCl₃/Montmorillonite K-10. The attractive features of this method are simple operation, high yields, short reaction time, and good regional selectivity, inexpensive and recyclable catalyst.β-Alkoxy alcohols are one of important synthetic intermediates, which can be used to oxide synthesize alkoxy ketones or alkoxy acids, as well as some other special drug intermediate compounds. In addition, it could selectively protect hydroxy to increase selection of organic synthesis. After refering to previous work and the specific experimental, we found amberlyst-15 serves as an inexpensive, effective, and environmental friendly heterogeneous catalyst for the regioselective ring-opening of epoxides by primary, secondary and tertiary alcohols, and result in the formation ofβ-alkoxy alcohols under ultrasound irradiation. Thus a new method has been developed for synthesis ofβ-alkoxy alcohols.In short, the epoxides ring opening reaction has shown a lot of advantages in organic synthesis, pharmaceutical synthesis and so on. For example: (1) Useness of their characteristics of easy preparation and ring-opening, to protect the functional groups; (2) Useness of the reaction of the highly stereo- and regio-selective of ring-opening, to stereo- and regio-selective synthesize organic compounds; (3) Useness of their characteristics which the ring-opening reaction will be directly translated into a new functional group, to synthesize the new chain-like compounds; (4) Useness of the small molecule ring-opening reaction, to synthesize biologically active natural substances.In conclusion, we studied three different types of ring-opening reaction of epoxides. This will provide a platform and open up a new path for the search for new reagents, the establishment of new methods and new theories. It will promote the development of organic synthetic chemistry.