Application of Counterattack Reagents Hexamethyldisilathiane and Hexamethyldisilane in Chemical Transformations and Development of Lignans as New Anti-HIV Agents

• Main Authors: Tseng, Wen Nan, 曾文男
• Other Authors: Hwu Jih Ru
• Format: Others
• Language: zh-TW
• Published: 1998
• Online Access: http://ndltd.ncl.edu.tw/handle/98157949020425684302

博士 === 國立清華大學 === 化學系 === 86 === In this thesis, the application of "counterattack regent" hexamethyldisilathiane on the accomplishment of a series of novel double functional group transformations was reported. Another counterattack regent hexamethyldisilane was used in the deoxygenation of various organic oxides. Furthermore, the derivatives of nordihydroguaiaretic acid (NDGA) were synthesized and characterized which act as a new class of anti-HIV agents. In Part 1 of this thesis, a series of novel double functional group transformations were established. These transformations convert nitrocycloalkenes to carbonyl or alkenyl nitriles in "one-flask" procedure. Sophisticated mechanisms are involved in these reactions. Various a-substituted ketoximes can also be prepared in good yields. In those efficient tandem processes, hexamethyldisilathiane acts as a counterattack reagent. In Part 2 of this thesis, deoxygenation of nitrones was achieved in excellent yields by use of hexamethyldisilane in the presence of methyl lithium. Similarly, heterocyclic N-oxides were converted to the corresponding heterocycles in high yields. These deoxygenation processes involve a new 1,2-elimination of intermediates containing Si-C-N-O moiety. In Part 3 of this thesis, the treatment of NDGA with dimethyl sulfate and potassium carbonate in acetone to give nine methylated products was reported. Eight of those mono-, di-, tri-, and tetra-O- methylated NDGAs were isolated. Among the eight different methylated NDGAs, tetra-O-methyl-NDGA exhibited the strongest anti-HIV activity. Lignans with methylated catecholic hydroxyl groups can be produced in large quantities with low cost to serve as new anti-HIV agent.