Synthesis and Thermolysis Mechanism of Oxetanes Containing a Highly Coordinate Main Group Element

1.合成了一个含马丁配体的五配位3-甲氧基甲氧基-1，2-氧杂环己烷，作为1，2-氧杂环己烷的第一个例子，在3-位带有一个吸电子基团，如羰基。合成了一种新型的含两个1，2-氧杂环磷烷的螺环磷烷。2.在18-冠-6存在下，将含有Martin配体的乙烯基硅烷与t-BuLi反应，再与羰基化合物反应，得到相应的β-羟基硅烷，然后与KH反应，得到Peterson反应的中间体--五配位1，2-氧杂硅烷。类似地，我们还合成了五配位的1，2-氧杂环己烷和1，2-偏氧杂环己烷，尽管前者不需要马丁配体的稳定作用。X-射线单晶分析表明这些化合物具有扭曲的三角双锥结构，在尖端位置有两个或一个氧原子(对于草甘膦)(S)。3.在Et_3N存在下，通过相应的双(羟基)硫化物与溴的氧化环合反应合成了四配位的1，2-氧杂硫杂环烷和1，2-氧杂硒杂环化合物，X-射线单晶分析表明它们都具有假三角双锥结构。4.第14族和第15族元素化合物的热分解通过一个轻微的极性过渡态定量地得到了相应的烯烃。然而，16族元素化合物的裂解不产生Wittig反应产物，而是硫氧键异质裂解引起的迁移产物。值得注意的是，在1，2-氧杂硫杂环己烷的热分解过程中，得到了微量的Corey-Chaykovski反应产物--环氧乙烷。这些结果已以简短通信的形式发布。

1. A pentacoordinate 3-methoxycarbony1-1,2-oxaphosphetane bearing the Martin ligand has been synthesized as the first example for 1,2-oxaphosphetane with an electron-withdrawing group such as carbonyl group at the 3-position. A novel type of spirophosphorane containing two 1,2-oxaphosphetane rings has also been synthesized successfully. 2. Pentacoordinate 1,2-oxasiletanides, intermediates of the Peterson reaction, have been obtained by deprotonation of the corresponding beta-hydroxy silanes, which were prepared by sequential treatment of the vinylsilane bearing the Martin ligand with t-BuLi and then with carbonyl compounds, with KH in the presence of 18-crown-6. Similarly, a pentacoordinate 1,2-oxastannetanide and 1,2-oxagermetanide have been synthesized, although stabilzation by the Martin ligand is not necessary in the former case.X-ray crystallographic analyzes of these compounds indicate that these compounds have a distorted trigonal bipyramidal structures with two or one (in the case of the oxastannetanide) oxygen atom (s) at the apical position (s) . 3. Tetracoordinate 1,2-oxatthietane and 1,2-oxaselenetane were synthesized by oxidative cyclization of the corresponding bis (hydroxy) chalcogenides with bromine in the presence of Et_3N.It was also indicated by X-ray crystallography that they have pseudo-trigonal bipyramidal structures. 4.Thermolyses of the group 14 and 15 element compounds gave quantitatively the corresponding olefins via a slightly polar transition state. However, themolyses of group 16 element compounds afforded no Wittig reaction products, but migration products induced by the heterolysis of the chalcogen-oxygen bond. It is very interesting to point out that a trace of Corey-Chaykovski reaction product, oxirane, was obtained in the case of thermolysis of 1,2-oxathietane. These results have been published as short communications.