碲氢化钠与苯并咪唑盐的反应和醛的合成新方法

自1975年Barton首次制备了碲氢化钠以来,由于它是一种温和的选择性还原剂和良好的亲核试剂,并具有试剂易得、后处理方便等优点,在有机合成中的应用得到了迅速发展[1-5].例如,Barton等[1]用碲氢化钠对吡啶盐和异喹啉盐的季铵化的碳氮双键在碱性乙醇溶液中还原脱卤能生成加氢衍生物.本文则首次报道碲氢化钠对苯并咪唑盐还原脱卤生成苯并咪唑烷的反应.其合成路线如图示1所示:     

Selective reduction of the N-O bond in n-oxides and in nitrones by sodium hydrogen telluride

Sodium hydrogen telluride reduces $\text{tert}$.-amine $\text{N}$-oxides to the corresponding amines in very high yield, but does not reduce sulphoxides. This reagent also reduces nitrones to $\text{sec}$.-amines at pH6 and to imines at alkaline pH (10–11).     

Selective reduction of vinylhydroxyphenyl azomethines by sodium borohydride

Conclusions Vinylhydroxyphenyl azomethines are reduced by sodium borohydride at room temperature only at the azomethine group.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2076–2078, September, 1978.     

Selective debenzylation of benzyl esters by silica-supported sodium hydrogen sulphate

A new debenzylation of benzyl esters by silica-supported sodium hydrogen sulfate is described. The debenzylation could be achieved selectively and efficiently in good to excellent yields without affecting sensitive functional groups such as nitro, unsaturated bonds, and ethyl ester.     

Selective debenzylation of aromatic benzyl ethers by silica-supported sodium hydrogen sulfate

A new debenzylation of aromatic benzyl ethers by silica-supported sodium hydrogen sulfate is described. The process proceeds selectively and efficiently in good to excellent yields without affecting sensitive functional groups such as nitro, COOMe, aldehyde, ketone, and tosyl.     

Selective reduction of nitro-heterocycles with sodium sulfide in aqueous p-dioxane

Nitro-heterocycles, particularly those containing halogen, were selectively reduced with sodium sulfide in aqueous p-dioxane to give the corresponding amino-heterocycles in 70-89% yields.     

Selective reduction of 1-chloro-2-iodoperfluorocycloalkenes with sodium trimethoxyborohydride

In contrast to other chemical reducing agents, it has been found that sodium trimethoxyborohydride will selectively reduce 1-chloro-2-iodoperfluorocycloalkenes to give good yields of 1-hydro-2-chloroperfluorocycloalkenes. The selective displacement of iodine by hydrogen is discussed in terms of HSAB principles.     

Sodium hydrogen telluride as a useful nucleophilic reagent for the cleavage of epoxides and of quaternary ammonium salts

Sodium hydrogen telluride opens many epoxides cleanly by an SN₂ process to give telluro-alcohols, which by reduction with nickel boride afford alcohols. An intermediate telluro-alcohol was converted to olefin in high yield by treatment with $\text{p}$-toluene-sulphonyl chloride in pyridine. Quaternary ammonium salt are also cleaved efficiently by sodium hydrogen telluride.     

Selective catalytic reduction of NOx by hydrocarbons enhanced by hydrogen peroxide over silver/alumina catalysts

It is shown that hydrogen peroxide enhances substantially selective reduction of NOx to nitrogen with hydrocarbons over Ag/alumina catalysts.     

Selective reduction of alkynes catalyzed by palladium acetate with sodium methoxide as the hydride source

Treatment of internal alkynes with sodium methoxide in the presence of Pd(OAc)₂ and PPh₃ in methanol for 48 h gave the reduction products, alkenes or alkanes in good chemical yields. This reaction proceeds through a palladium methanolate complex, followed by β-hydride elimination and reductive elimination.     

Sodium hydrogen telluride: a mechanistic chameleon

Relative rates of reduction of several ,β-unsaturated esters andstyrenes added to recently obtained results from other substrates show that sodium hydrogen telluride (NaTeH) can react according to different mechanisms: nucleophilic substitution, hydride transfer, hydrogen atom transfer and electron transfer.

Relative rates of reduction by HTeNa in addition to some other known results indicate that HTeNa reacts by different pathways according to the substrate and reaction conditions.     

Surface modification by electrochemical reduction of alkyldiazonium salts

Since alkyldiazonium salts are highly unstable, their grafting is not as easy as that of aryldiazonium salts. However, it is possible to graft alkyl chains on copper electrodes by the in situ reaction of alkyl amines dissolved in aqueous perchloric acid with nitrite ions electrogenerated from nitrate ions.     

Organic tellurium compounds—VIII Di-aryl tellurides as dehalogenation agents —the reduction of metallic salts by DI-p-tolyl telluride

The reaction of di-p-tolyltelluride with ferric, cupric and mercuric chloride, performed in glacial acetic acid, effects the reduction of the metallic salts giving rise to di-p-tolyltellurium dichloride. In toluene solution only the ferric chloride was reduced and the anhydride of di-p-tolyltellurium hydroxychloride formed, due to the hydrolysis of the tellurium dichloride. The reaction of the mentioned telluride and benzoyl chloride gave rise to a mixture of the dichloride and the dibenzoate. The mechanism of this reaction is discussed.     

Selective reduction of carbonyl compounds by diphenylstibine

Carbonyl compounds were selectively reduced by diphenylstibine in the presence of Lewis acid.