Synthesis and Structures of the Intermediates of the Wittig, Peterson, and Their Related Reactions

Abstract

Pentacoordinate oxaphosphetanes, oxasiletanides, oxagermetanides, oxastannetanides, and tetracoordinate oxaboretanides were successfully synthesized as stable intermediates of the Wittig reaction, the Peterson reaction, Peterson-type reactions, and boron-Wittig reaction, respctively. Tetracoordinate and pentacoordinate oxathietanes, tetracoordinate oxaselenetanes and pentacoordinate azaphosphetidines were also synthesized as their sulfur and selenium-analogs, and aza-analog of oxaphosphetanes. The X-ray crystallographic analyses of Si, Ge, P, S, and Se compounds indicated that they have a distorted trigonal bipyramidal structure with two apical oxygen atoms, but those of B, Sn, and another type of Ge compounds demonstrated that they have a very distorted tetrahedral boron, a nearly square pyramidal tin, and a tetrahedral germanium strongly interacting with an oxido anion, respectively. Expectedly, on heating all compounds containing group 13, 14, and 15 elements underwent the Wittig-type reaction to give the corresponding olefins. Although the thermolysis of oxachalcogenetanes with a tetracoordinate and pentacoordinate S and Se centers gave no olefin, it was suggested that the former compounds are intermediates of the Corey-Chaykovsky reaction of sulfur ylides.