STUDIES ON FORMATION OF REACTIVE SPECIES USING ORGANOMETALLIC COMPOUNDS OF GROUP 4B ELEMENTS AND THEIR APPLICATIONS TO ORGANIC SYNTHESIS

利用有机金属试剂合成活性合成中间体的研究一直是人们关注的焦点，而有机金属试剂是用其他方法难以制备的。我们证明了-杂原子取代的有机硅化合物的1，3-消除是很容易实现的，并且在温和的条件下，从合成和理论上看，最重要的1，3-偶极化合物--不稳定的甲亚胺叶立德和硫代羰基叶立德都能非常顺利地得到。这构成了一条合成母体偶氮亚胺叶立德和硫代羰基叶立德的前所未有的便利途径。(1)分别作为偶氮亚甲基叶立德和硫代羰基叶立德的容易制备的N-(硅甲基)氨基甲醚和氯甲基硅甲基硫化物，在缺电子的烯烃、羰基化合物和N-杂芳烃存在下，通过路易斯酸或氟化铯选择性地激活碳-氧和碳-氯键，得到相应的吡咯烷、四氢噻吩环、1，3-氧硫杂环戊烷，(2)我们发现了作为2，2‘-联烯丙基二自由基和2，2’-联烯丙基两性离子合成子的2-dimethylaminomethyl-3-trimethylsilylmethyl-1，3-butadiene的简便制备和串联环加成反应。(3)五配位烯丙基硅酸酯及其相关化合物，迄今未知，可以很容易地制备出来，并作为亲核试剂用于高度化学、区域和立体选择性还原和烯丙化反应。

Much attention has been focused on the conventional generation of active synthetic intermediates using organometallic reagents which are hard to prepare by other method. We demonstrate that 1,3-elimination of -heteroatom substituted organosilicon compounds can be readily achieved and that non-stabilized azomethine ylides and thiocarbonyl ylide which are the most important 1,3-dipoles from both synthetic and theoretical points of view are obtained very smoothly under mild conditions. this constitutes an unprecedented and expedient route to parent azomthine ylide and thiocarbonyl ylide.(1) N-(Silylmethyl)aminomethyl ethers and chloromethyl silylmethyl sulfide as azomethine ylide and thiocarbonyl yilde synthous, respectively, readily prepared, undergo the activation of the carbon-oxygen and carbon-chlorine bond selectively by the Lewis acid or cesium fluoride in the presence of electron deficient alkenes, carbonyl compounds and N-heteroaromatics, to give the corresponding pyrrolidines, tetrahydrothiophenes, 1,3-oxathiolanes, and 1,3-thiazolidines in considerably high yield.(2) We found a convenient preparation and tandem cycloaddition reactions of 2-dimethylaminomethyl-3-trimethylsilylmethyl-1,3-butadiene that serves as 2,2'-biallyl diradical and 2,2'-biallyl zwitterion synthons.(3) Pentacoordinate allylsiliconates and related compounds, unknown hitherto, can be readily prepared and used as uncleophiles for the highly chemo-, regio- and stereo-selective reduction and allylation.