Development of New Functions of Organochalcogenic Compounds and Its Development

本研究主要基于“手性含硒化合物的空间大小和氢键稳定”的概念，以2-外羟基-10-龙脑基作为手性配体，为手性硒氧化物、硒、碲等手性化合物的制备提供了一种新的方法。在卤化硒与氧化硒的相互转化反应和亲核取代反应中，观察到了该构型的完全保留。例如，氯硒与活性亚甲基化合物的亲核取代反应以高度立体选择性的方式进行，并保持构型不变，得到相应的硒叶立德。b)手性碲化合物的不对称合成首次以2-外-羟基-10-龙脑基为手性配体，首次合成和分离了光学纯的手性碲-烷氧基碲烷。C)不对称烯醇酸酯的不对称质子化反应以2-外-羟基-10-龙脑基为手性质子源的光学纯伽马-羟基-硒氧化物为手性质子源，发展了简单烯醇酸的不对称质子化反应。ii)烯丙基硒化合物的不对称[2，3]Sigmatroic重排烯丙基硒亚胺的[2，3]Sigmatroic重排主要通过Endo过渡态进行，可用于各种手性烯丙胺的实际制备。该方法适用于各种手性烯丙基硒氧化物和高烯丙基化合物的制备。

This investigation is mainly based on the concept "Stabilization of chiral chalcogenic compounds by the stericbulkiness and the hydrogen bonding", which provides a novel method for the preparation of chiral chalcogenic compounds such as chiral selenoxides, selenuranes, and telluranes by using 2-exo-hydroxy-10-bornyl group as a chiral ligand.A) Asymmetric synthesis of chiral selenium compoundsThe first synthesis of optically pure haloselenuranes has been accomplished by utilizing the 2-exo-hydroxy-10-bornyl group as a chiral ligand. Complete retention of the configuration has been observed in inter-conversion reactions between haloselenuranes and selenoxides and in nucleophilic substitution reaction of those haloselenuranes. For example, nucleophilic substitution reaction of the chloroselenurane with active methylene compounds proceeded in highly stereoselective manner with retention of configuration to give the corresponding selenonium ylides.B) Asymmetric synthesis of chiral tellurium compoundsThe first synthesis and isolation of optically pure Te-chiral-alkoxytelluranes have been developed using the 2-exo-hydroxy-10-bornyl group as a chiral ligand. A distorted trigonal bipyramidal structure was confirmed by the X-ray analysis.C) Asymmetric reaction utilizing chiral selenoxidesi) Asymmetric protonation of enolatesEnantioselective protonation of a simple enolate has been developed using an optically pure gamma -hydroxy- selenoxide having the 2-exo-hydroxy-10-bornyl group as a chiral ligand as a chiral proton source.ii) Asymmetric [2,3] sigmatropic rearrangement of allylic selenium compoundsThe [2,3] sigmatropic rearrangement of allylic selenimides proceeds predominantly via the endo transition state, and is available for practical preparation of various chiral allylic amines. The methodology is applicable to the preparation of of various chiral allylic selenoxides and homoallylic compounds.