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The Research on the Synthesis of Diselenides、Tegafur Diselenides and Organoselenium Sugars by the Catalysis of Cesium Ion

Author: LiRuoXin
Tutor: XuXinHua
School: Hunan University
Course: Organic Chemistry
Keywords: Cesium Carbonate 80% Hydrazine Monohydrate Diselenides Nucleoside Tegafur Diselenides Sugar Diselenides Sugar selenides Cesium chloride
CLC: O627.61
Type: Master's thesis
Year: 2009
Downloads: 105
Quote: 1
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Abstract


Selenium, which has important physiological actions, is one of the essential trace elenments for people. Lack of selenium will lead to a series of diseases, such as Cataract, Keshan disease, Kedney disease, et al. For the last 30 years, People have synthesized lots of organic selenides which have biological activity.And among them, two of much more important kinds are selenides and diselenides. Most diselenides are potential drugs and drug pharmaceuticals for their biological activities, such as antioxidation, antitumor, antimicrobial and antiviral properties because of Se-Se bond in the structure. Furthermore, diselenides are of especial significance in organic synthesis. These compounds can act as electrophilic reagents, for example, in addition to double bonds, as well as nucleophilic reagents for the syntheses of allylic alcohols and amines. Since the early nineties, diselenides have been employed in asymmetric syntheses, for example,in the asymmetric opening of epoxides, in hydroxy and methoxyselenylation , and others.There are two classic methods to synthesize diselenides. The first method is oxidation of the products of reacting Grignard reagents with selenium, which need strict anhydrous operation. The convinent route to diselenides is reaction of alkyl tosylates with sodium diselenides which was obtained by reduction of selenium by hydrazine hydrate. But this method isn’t suitable to synthesize diselenides involving functional groups but is suitable to synthesize dialkyl diselenides because of limit of the high temperature in the method. In this paper, we design and synthesize the sodium diselenide first by the reaction of selenium with 80% hydrazine monohydrate, then the diselenides are formed based on the nucleoplilic substitution reaction of the sodium diselenide with alkyl halides or tosylates by the catalysis of cesium carbonate, according to the principle that cesium ion can activate anion binding with it. The result shows that the reaction can be carried out effectively at room temperature, and the production rate is above 70%.It is difficult to synthesize tegafur diselenides by other means because of many functional groups within tegafur, and the synthesis of tegafurs diselenides haven’t been reported at present. In this paper, we design and synthesize tegafur diselenides by the catalysis of cesium carbonate. The result shows that the reaction can be carried out quickly at room temperature, and we obtain several novel compounds of tegafur diselenides.Organoselenium sugars have high biological activities and mainly distribute within plants, animals and microorganism, especially within the plants. But the lower content of natural organoselenium sugars in them limit the application. In recent years, lots of organoselenium sugars were obtained from zymosis or extraction from plants rich in selenium or synthesis by chemical processes, while the synthesis of sugar selenides and diselenides by the catalysis of cesium ion haven’t been reported at present. In this paper, we design the synthesis of symmetrical sugar diselenides and sugar selenides by the catalysis of cesium carbonate and cesium chloride. The result shows that reaction can be carried out quickly and conveniently at room temperature.

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CLC: > Mathematical sciences and chemical > Chemistry > Organic Chemistry > Elements in organic compounds > Part Ⅵ group element compounds ( oxygen and sulfur are excluded) > Selenium and tellurium organic compounds
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