Novel preparation method and synthetic applications of cyclopropyl trimethylsilyl ketones

通过1-三甲基硅基环丙基锂衍生物与二氯甲基甲醚的新反应，以中等产率合成了一系列新的环丙基三甲基硅基酮。该反应涉及分子内1，2-硅从碳到碳的转移。测定了这些硅基酮的光谱性质，所得的酮与各种卤素酸在较温和的条件下反应生成开环产物3-氯丙基硅酮或扩环产物2-硅基-4，5-二氢呋喃衍生物。与硫酸或三氟甲烷磺酸反应，只得到相应的硅基二氢呋喃，产率较高。特别值得注意的是，2-苯基环丙基硅酮与硫酸反应生成了2-苯基环丁酮。这些角点的形成是基于硅稳定阳离子的作用…解释的此外，环丙基硅基酮与亚烷基三苯基膦的Wittig反应以立体选择性进行，得到相应的Z-1-硅基-1-环丙基烯烃。硅基环丙基烯与四丁基氟化铵的原脱硅反应保持构型，生成E-环丙基烯，与卤化氢的反应因三元环的断裂而失败，四氢呋喃中的硫叶立德与环丙基硅酮反应生成相应的硅氧基烯或-酮硅烷。这些化合物的相对比例随反应温度、所用溶剂的比例和叶立德的制备方法而变化。值得注意的是，与无盐叶立德的反应选择性地提供了硅氧基烯和含有无机盐酮硅烷的叶立德的反应。这两种产物可能是甜菜碱中间体中硅基的阴离子和阳离子重排形成的。较少

A series of new cyclopropyl trimethylsilyl ketones has been prepared in moderate yield from the novel reaction of 1-trimethylsilylcyclopropyllithium derivartives with dichloromethyl methyl ether. This reaction involves the intramolecular 1,2-silicon shift from carbon to carbon. The spectroscopic properties of these silyl ketones have been measured.The ketones obtained here react with various halogen acids under milder conditions compared to that of their carbon analogs to give the ring opening products, 3-chloropropyl silyl ketones, or the ring enlargement products, 2-silyl-4,5-dihydrofuran derivatives in some cases. The reaction with sulfuric acid or trifluoromethane sulfonic acid affords only the corrensponding silyldihydrofurans in good yield. Especially, it is noteworty that the reaction of 2-phenylcyclopropyl silyl ketone with sulfuric acid yields 2-phenylcyclobutanone. The formation of these comounds is interpreted on the basis of the effect that silicon stabilizes a cation to it … More .Wittig reactions of cyclopropyl silyl ketones with alkylidene-triphenylphosphoranes proceed stereoselectively to give the corresponding Z-1-silyl-1-cyclopropyl alkenes. The protiodesilylation of silyl cyclopropyl alkenes with tetrabutylammonium fluoride proceeds with retention of configuration to give E-cyclopropyl alkenes, although the reaction with hydrogen halides was unsuccessful due to the cleavage of the three membered ring.The reaction of sulfur ylides in THF with cyclopropyl silyl ketones resulted in the formation of the corresponding siloxyalkenes or -ketosilanes. The relative ratio of these compounds varies with the reaction temperature, the porality of solvents used, and the preparation method of ylide. It is noteworthy that the reaction with salt free ylide affords siloxyalkenes and that of the ylide containing inorganic salt -ketosilanes, selectively. These two type of products would be formed by the anionotropic and cationotropic rearrangement of silyl group in the betaine intermediate. Less