Reductive Cleavage of the Te—Te Bond in Diphenyl Ditelluride by the Sm—CrCl3（cat.）System： Preparation of Telluroesters and Unsymmetrical Phenyltellurides

The reduction of diphenyl ditelluride by the Sm/CrCl3(cat.) system led to a telluride anion.This species reacted with acid chlorides,alkyl halides,and α，β-unsaturated enoates or α，β-unsaturated ene nitriles to afford telluroesters and unsymmetrical phenyltellurides,respectively,in moderate to good yields under mild and neutral conditions.     

有机碲Ylide反应Ⅻ用碲Ylide合成双环丙烷衍生物

由相应的碲盐生成的某些碲ylide,能顺利地和1,4-双(3-取代苯基-3-酮-1-丙烯基)苯,1,5-二取代苯基-1,4-戊二烯-3-酮反应生成双环丙烷衍生物,反应具有高立体选择性,产率为61.8-88.8％。     

用碲ylide合成杂环查尔酮,二烯酮和杂环烯类衍生物

最近,我们用碳酸钾作碱从碲盐在含微量甲酰胺的乙腈中,手室温条件下十分简便地合成了2-或2,4-不饱和腈,酮,酯和酰胺。杂环查尔酮和5-硝基呋喃烯类化合物都是具有生理活性的化合物。为扩大碲ylide的应用并研究杂环基团引入对碲ylide反应活性的影     

有机碲化合物的~(125)Te NMR研究

本文测定了三个有机碲盐化合物以及一些碲醚类化合物的~(125)Te NMR谱。得到了这些化合物的~(125)Te化学位移值。主要讨论了影响~(125)Te化学位移的因素。通过实验,我们可以得出如下的结论:与Te相连取代基的电负性增强,~(125)Te化学位移值增大。化合物中,碲的成键性质不同,~(125)Te化学位移值也有所不同。碲盐类化合物的~(125)Te化学位移值受溶液浓度及溶剂性质的影响比较大,浓度加大,~(125)Te化学位移向高场移动,而且变化较明显。溶剂的极性增强,~(125)Te化学位移向低场移动。     

火焰原子吸收光谱法测定硒碲混合物中碲的研究

本文建立了酒石酸-硝酸盐酸混酸溶解样品,在王水-酒石酸介质中,采用空气-乙炔火焰在原子吸收光谱仪上测定硒碲混合物中的碲的方法。本实验研究了样品处理方法、乙炔流量、燃烧高度、灯电流、溶液介质等有关工作条件。实验表明碲浓度在1～20ug/mL范围内与吸光度呈良好的线性关系,回归方程为A=0.0229C 0.0009,相关系数0.9998,检出限0.08ug/mL,本方法适合于硒碲混合物中碲的测定,相对标准偏差为0.9%～1.3%,回收率为98%～102%。     

火焰原子吸收光谱法测定硒碲混合物中的碲

建立了酒石酸-硝酸-盐酸混酸溶解样品,在王水-酒石酸介质中,采用空气-乙炔火焰在原子吸收光谱仪上测定硒碲混合物中碲的方法。研究了样品处理方法、乙炔流量、燃烧高度、灯电流、溶液介质等有关工作条件。实验表明碲浓度在1～20μg/mL范围内与吸光度呈良好的线性关系,回归方程为A=0.0229C+0.0009,相关系数0.9998,检出限0.08μg/mL。适合于硒碲混合物中碲的测定,相对标准偏差为0.9%～1.3%,回收率为98%～102%。     

用碲Ylide合成杂环取代环丙烷衍生物

本文报道了由碲盐和杂环取代查尔酮反应合成杂环取代环丙烷衍生物的简便方法。     

2，4-共轭不饱和酮、酯、腈的合成

前文我们报道了溴化对-苯基苯甲酰甲基二丁基碲、溴化对-溴苯甲酰甲基二丁基碲和溴化间-硝基苯甲酰甲基二丁基碲等碲盐与醛、酮缩合成α,β-不饱和酮的反应。为了进一步研究碲盐反应性能,扩大它在有机合成中应用范围,我们在前期工作基础上,由碲盐和(E)-α,β-不饱和醛合成了2,4-共轭不饱和酮、酯、腈,这是一种未见文献报道的新合成方     

A facile synthesis of polyfoluoroalkyl-lactonization

2(-Benzoxazolyl substituted cyclopropane derivatives were synthesized in the yield of 73-89% from the reaction of telluronium ylides with chalcones.     

A Facile Synthesis of Benzoxazolyl Cyclopropanes

2′-Benzoxazolyl substituted cyclopropane derivatives were synthesized in the yield of 73-89% from the reaction of telluronium ylides with chalcones.     

Chalcogen Chiral Ylides for the Catalytic Asymmetric Epoxidation of Aldehydes: From Sulfur to Selenium and Tellurium

Abstract

The reaction of novel chiral selenonium and telluronium ylides was investigated with aldehydes and compared to the sulfur analogues. (2R,5R)-2,5-Dimethylselenolane was prepared and reacted as a catalyst for the benzylidenation of aldehydes. Disubstituted epoxides were readily prepared with a (surprising) absence of diastereoselectivity, and with enantiomeric excesses higher than 90%. The reaction of a tellurium analogue, (2S,5S)-2,5-diethyltellurolane, afforded the oxirane in very moderate yield and e.e.'s in the range of 62–82%. Though this was less productive, it is the first report of a chiral telluronium ylide leading to an asymmetric epoxidation of aldehydes.     

Selenium- and tellurium-based ionic liquids and their use in the synthesis of octahydroacridines

A general and easy method for the synthesis of several selenonium and telluronium salts is described. These compounds are acidic liquids at room temperature and were obtained in excellent yields. Phenyl butyl ethyl selenonium tetrafluoroborate was employed in the hetero-Diels-Alder cyclization of aryl imines derived from citronellal, affording octahydroacridines in good yields.     

Synthesis and Stereochemistry of Optically Active Selenium and Tellurium Compounds

Abstract

The synthesis and stereochemistry of tricoordinated optically active selenium and tellurium compounds are described. Telluronium salts, telluronium imides, and seleninic acids were prepared and optically resolved by fractional recrystallization of diastereomeric mixtures or by chromatography using a chiral column of racemic mixtures. Diphenyl dichalcogenides also were optically resolved by chiral crystallization. Their absolute configurations were determined or estimated based on X-ray crystallographic analysis, specific rotations, and circular dichroism spectra. The kinetic studies and the mechanism for the racemization were also studied.     

Developments on the Chemistry of Tellurium and Selenium Azides

Abstract

We have been carrying out systematic studies on the preparation and properties of tellurium halide and pseudohalide compounds with a focus on tellurium azides. We were successful in the synthesis of various tellurium azides of both covalent and ionic nature. Several tellurium(IV) azides, tellurium(II) azides, and the first tellurium(VI) azides can be prepared in reasonable amounts. The first structural information of selenium azides is obtained for covalent and ionic derivatives, and spectroscopic data for the existence of selenium(iv) polyazides.