Studies on Stereoregulated Reaction Using Organosilicon Reagents and Highly Selective Synteses of Heterocyclic Compounds

近年来，四配位烯丙基硅烷的合成及其在有机合成中的应用引起了人们的广泛关注。硅烯丙基西格马键热稳定的烯丙基硅烷被转移到由Lewis酸激活的碳亲电体上，具有很高的区域、立体和化学选择性。有机硅化学中最有趣的特征之一是可以分离出稳定的高配位物种。在有机硅化合物在有机合成中的延伸中，我们发现迄今未知的五配位烯丙基硅酸酯及其相关化合物可以很容易地制备并用作亲核剂，其中一些是报道的。主题是：(1)有用的、可储存的烷氧基取代的五配位烯丙基硅酸酯的制备，羰基化合物在无催化剂的情况下的区域、化学和立体选择性的烯丙基化反应，以及与光学活性的烯丙基硅酸酯的不对称烯丙基化反应的立体化学结果，这些结果由六元环过渡态解释，与反S和E‘GT形成鲜明对比；(2)使用三烷氧基硅烷和碱金属醇盐衍生的烷氧基取代的氢硅酸酯对羰基化合物的化学和立体选择性还原，以及使用氢硅酸盐对前手性酮的新的催化不对称还原。(3)钯配合物催化的烯基硅酸盐与有机卤化物和三氟化物的立体选择性交叉偶联反应。(4)合成了难以获得和分离的高活性物种，合成了相当于亚烷基偶氮亚甲基叶立德的有机硅试剂，并允许它们与烯烃、羰基和硫代羰基化合物反应，高产率地得到相应的[3，2]环加合物。

Much attention has been recently focused on both syntheses of tetracoordinate allylsilanes and their applications to organic synthesis. Allylsilanes whose silicon-allyl sigma-bond is thermally stable can be highly functionalized allvl are transferred onto carbon electrophiles activated by a Lewis acid with high regio-, stereo- and chemoselectivity. One of the most interesting features in organosilicon chemistry is that stable high coordinate species can be isolated. In an extension of organosilicon compounds in organic synthesis, we have found that pentacoordinate allylsiliconates and related compounds, unknown hitherto, can be readily prepared and used as nucleophiles, some of which are reported.Topics are (1) preparations of pentacoordinate allylsiliconates, substituted by alkoxy groups, which are useful and storable reagents, regio-, chemo- and stereoselective allylations of carbonyl compounds without catalyst, and stereochemical outcomes of asymmetric allylation with optically active allylsiliconates which are interpreted by a six-membered cyclic transition state, in sharp contrast with an anti-S_<E'> mechanism for the allylation using tetracoordiante allylsilane, (2) Chemo- and stereoselective reductions of carbonyl compounds using alkoxy-substituted hydridosiliconates derived from trialkoxysilane and alkali metal alkoxides, and new catalytic asymmetric reductions of prochiral ketone using hydridosiliconates. (3) Cross-coupling reactions of alkenylsiliconates with organic halides and triflates catalyzed by a palladium complex in a stereoselective mode. (4) Syntheses of highly reactive species which were hardly obtainable and not isolable were achieved, Organosilicon reagents that acted as a synthetic equivalent of alkylideneazomethine ylids were prepared and allowed to react with alkenes, carbonyl and thicarbonyl compounds to give the corresponding [3+2] cycloadducts in high yields.