STUDIES ON NOVEL ORGANIC REACTION AND STEREO-REGULATION USING SILICON-, TIN-, AND RELATED ELEMENT COMPOUNDS

1.五配位有机硅的高选择性烯丙基化反应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。我们发现，五配位烯丙基硅酸盐和相关化合物，迄今未知，可以很容易地制备和用作亲核试剂，其中一些报道。主题是制备五配位烯丙基硅酸盐，被烷氧基取代，这是有用的和可储存的试剂，羰基化合物的区域化学和立体选择性烯丙基化无催化剂，和立体化学结果的不对称烯丙基化与光学活性烯丙基硅酸盐，这是解释为一个六元环状过渡态，与使用四配位烯丙基硅烷的烯丙基化的反SE ^1机理形成鲜明对比。2亚烷基偶氮甲碱产物的新合成及相关1，3-偶极试剂及其在有机合成中的应用从合成和理论的角度来看，甲亚胺叶立德和相关的1，3-偶极试剂都是重要而有趣的化学物种。如果偶极中心没有被吸电子或共轭基团稳定，这些物质通常是不稳定的和不可接近的。本文报道了在氟化铯存在下，N-甲硅烷基甲基取代的烯酮N，S-缩醛与活化烯烃、羰基化合物和硫酮通过甲硫基三甲基硅烷的1，3-消除反应，顺利地生成了α-亚烷基吡咯烷、恶唑烷和噻唑烷。类似地，N-硅甲基取代的异硫脲在氟离子的促进下与羰基和硫代羰基化合物反应，得到相应的[3 + 2]环加成物2-亚氨基-1，3-恶唑烷和2-亚氨基-1，3-噻唑烷。这些试剂可被视为亚烷基甲亚胺叶立德和亚氨基甲亚胺叶立德的合成等价物。

1. Highly Selective Allylation Using Pentacoordinate Organosilicates On of the most interesting features in organosilicon chemistry is that stable high coordinate species can be isolated. We have found that pentacoordinate allylsilicates and related compounds, unknown hitherto, can be readily prepared and used as nucleophiles, some of which are reported. Topics are preparation of pentacoordinate allylsilicates, 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 allylsilicates which are interpreted by a six-membered cyclic transition state, in sharp contrast with an anti-SE^1 mechanism for the allylation using tetracoordinate allylsilane.2 Novel Synthesis of Alkylideneazomethine Yilds and Related 1,3-Dipolar Reagents and Synthetic Application to Organic Synthesis^2 Azomethine ylids and related 1,3-dipolar reagents are important and interesting chemical species from both synthetic and theoretical points of view. These species are generally unstable and inaccessible if the dipolar centers are not stabilized by electron-withdrawing or conjugating groups. We report here that a variety of N-silylmethyl-substituted ketene N,S-acetals react smoothly with activated alkenes, carbonyl compounds, and thioketones in the presence of cesium fluoride, to afford alpha-alkylidenepyrrolidines, oxazolidines, and thiazolidines, via a 1,3-elimination of methylthiotrimethylsilane. Similarly, N-silylmethyl- substituted isothioureas react with carbonyl and thiocarbonyl compounds promoted by fluoride ion to give the corresponding [3 + 2] cycloadduct, 2-imino-1,3-oxazolidines and 2-imino-1,3-thiazolidines in good yield. These reagents can be viewed as synthetic equivalents of alkylideneazomethine ylids and iminoazomethine ylids.