Study On Applications Of (Z)-α-Silylvinyl Grignard Reagents In High Selective Synthetic Reactions

This dissertation describes the applications of 1,1-difunctional group reagent-(Z)-a-silylvinyl Grignard reagents in high selective synthetic reactions.According to the literature procedure, (Z)-alpha-silylvinyl Grignard reagents were prepared by hydromagnesiation of alkynylsilanes. We have studied the cross coupling reaction of (Z)-a-silylvinyl Grignard reagents with alkenyl halides catalyzed by PdCPPhsX which provides a new route to stereoselective synthesis of 1,3-dienyl-silanes .(Z)-a-Silylvinyl Grignard reagents were allowed to react with alkynyl iodides in the presence of Pd(PPh3)4, 1,3-enynylsilanes were obtained in good yields stereo-selectively.We have developed a novel approach to stereoselective synthesis of 1,4-dienyl-silanes by the cross-coupling reaction of (Z)-a-silylvinyl Grignard reagents and allylic chlorides in THF. 1,4-Dienylsilanes can undergo a desilylation reaction in the presence of a catalytic amount of hydriodic acid at room temperature in benzene to present a practical route to the stereoselective synthesis of 1,4-dienes.We have provided a facile route to stereoselective synthesis of (E)-alpha-aryl tellurenylvinylsilanes by the reaction of (Z)-a-silylvinyl Grignard reagents with aryl-tellurenyl iodies. (E)-alpha-Aryltellurenylvinylsilanes can react with Grignard reagents in the presence of Ni(PPh3)2Cl2 to afford (Z)-l,2-disubstituted vinylsilanes stereo-selectively in good yields .We have also found that (Z)-a-silylvinyl Grignard reagents can react with trialkyl stannyl chlorides to give (E)-a-silylvinylstannanes in good yields. Another method for preparing (Z)-l,2-disubstituted vinylsilanes has been provided by (Z)-a-silylvinyl-stannanes reacting with aryl iodides in the presence of Pd(PPh3)4 and CuI.