复合还原剂硼氢化钠/三氯化铁对亚砜的还原

硼氢化钠是一种温和、高选择性的亲核还原剂。一般它只能还原醛、酮和酰氯,而对其它功能团不起作用。因而其应用范围有一定的限制。据文献报道,某些金属卤化物能有效地提高硼氢化钠的还原性能^[1]。复合还原剂硼氢化钠/三氯化铁已应用于将β-二烷基氨基共轭烯酮还原为相应的饱和γ-氨基醇^[2]。本文研究了硼氢化钠/三氯化铁对亚砜的还原反应。     

Reduction of O-Acyl Oximes with Sodium Borohydride/Iodine System

O-acyl derivatives of aldoximes and ketoximes are reduced in good yields to the corresponding amines with sodium borohydride-iodine system.     

Reduction of Solid Benzophenones with Sodium Borohydride

The solvent-free reduction of benzophenone and five substituted benzophenones with sodium borohydride to the corresponding alcohols was studied by thermal analysis, X-ray powder diffractometry, NMR spectroscopy, and scanning electron microscopy. In most cases, the reaction occurs via liquid eutectic phases that are formed between the benzophenone and the resulting benzohydrol. Nevertheless, this reaction can be carried out without the need for a solvent, leading to pure alcohol without side products. In some cases, heating may be necessary to achieve a reasonably short reaction time. In conclusion, this reaction type appears to be feasible as a preparative organic reaction that avoids a solvent.This revised version was published online in November 2005 with corrections to the Cover Date.     

Mild and Efficient Deoxygenation of Sulfoxides with MoCl5/Indium System

It has been demonstrated that dialkyl, diaryl, and aryl alkyl sulfoxides can be efficiently converted into the corresponding sulfides by the reaction with a MoCl₅/In system in good to excellent yields under mild conditions.     

Deoxygenation of Acylferrocenes with Sodium Borohydride and Zinc Chloride

A mild procedure for the reductive deoxygenation of α-ferrocenyl aldehydes and ketones is reported using sodium borohydride and zinc chloride. The present method allows synthesis of alkylferrocenes containing functionalized tethers and is adaptable to large-scale preparations.     

Selective Reduction of Thiol Esters with Sodium Borohydride

A couple of years ago, Fujita and co-workers¹ reported the reduction of 2-thiazoline-2-thiol esters to alcohols with sodium borohydride in aqueous tetrahydrofuran. In connection with an ongoing synthetic project which requires the selective reduction of a stable acid derivative to the alcohol level in the presence of nitrile and ester groups, we examined the reaction of a variety of thiol esters with sodium borohydride. Our results show that the highly reactive (and thus unstable) 2-thiazoline-2-thiol ester derivatives are unnecessary and in fact various types of thiol esters are readily convertible to alcohols under mild conditions which do not effect the reduction of common acid derivatives such as nitrile, ester, and amide.     

Mild and Efficient Deoxygenation of Sulfoxides with a WCl6/Indium System

Dialkyl, diaryl, and aryl alkyl sulfoxides can be rapidly converted to the corresponding sulfides with a WCl₆/In system in excellent yields under mild conditions.     

Selective Reduction Among Carboxylic Acids with Sodium Borohydride

The selective reduction among carboxylic acids via acyloxyborohydrides derived from sodium borohydride and carboxylic acid mixture is demonstrated.     

脂肪族酯基选择性还原模型的建立

以不同烷基取代的酯作为模型, 对其进行NaBH4还原研究. 不同取代基酯的起始反应温度和半衰期显示出了明显的差别和一定的选择性; 用B3LYP/6-31++G(d,p)//HF/6-31G(d,p)方法计算得到的过渡态能量与实验得到的活化能变化趋势一致; 实验中观察到了奇偶碳效应; 对NaBH4还原酯基的溶剂影响进行了初步研究.     

Facile and Mild Reduction of Sulfoxides to Sulfides with TiCl4/Sm System

TiCl₄/Sm system reduces sulfoxides rapidly to the corresponding sulfides in good yields in THF at room temperature.     

Steric Effects in the Reduction of Ketones with Sodium Borohydride

The rates for the reduction of ketones with sodium borohydride are interpreted in terms of two parameters, both derived from force-field calculations; i.e. the strain difference between alcohol and ketone (Δ strain) and the steric hindrance towards approach of the hydride R. Models for the evaluation of R are discussed. With this approach reduction rates over a range of 10⁸ can be rationalized within a factor of 6–10.     

Mild and Efficient Deoxygenation of Sulfoxides to Sulfides with Cp2TiCl2/Gallium System

The Cp₂TiCl₂/Ga system was found to be a new reagent for reducing a variety of sulfoxides to the corresponding sulfides in good to excellent yields under mild conditions.      

An Efficient Method for the Reduction of Cephalosporin Sulfoxides

An efficient and convenient method for the reduction of cephalosporin sulfoxides to their corresponding sulfides by Lawesson reagent is reported.     

Mild and Efficient Deoxygenation of Sulfoxides to Sulfides Using HfCl4/KBH4 System

HfCl₄/KBH₄ was found to be a facile, efficient, convenient, and chemoselective system for the deoxygenation of dialkyl, diaryl, and aryl alkyl sulfoxides, especially for the reduction of dibenzyl sulfoxide to the corresponding sulfides under mild conditions. In addition, the HfCl₄/KBH₄ system could be used in reduction of some other sulfur-bearing substrates to the corresponding sulfides, such as 2,2′-dibenzothiazolyl disulfide, but this reducing system could not reduce sulfolane, diphenyl sulfone, p-toluenesulfonic acid, and p-toluenesulfonyl chloride to their corresponding thiophenols.     

Asymmetric Reduction of Acetoacetic Ester by Chirally Modified Sodium Borohydride

Asymmetric reduction of acetoacetic ester(6) was carried out by chirally modified NaBH₄. Under the present conditions, ethyl β-hydroxybutyrate(8) was obtained in high chemical yield (optical yield 8-19%).     

Microwave-Assisted Solid Reaction: Reduction of Ketones Using Sodium Borohydride

A general and efficient procedure for microwave-assisted reduction of liquid and solid ketones using sodium borohydride without solvents is described. The added support can enhance both the efficiency and chemoselectivity of reduction.     

金属氯化物对硼氢化钠还原α-氯代苯乙酮的影响

用NaBH₄还原α-氯代苯乙酮制备相应的β-氯代-α-苯乙醇时, 在较高的反应温度下产生许多副产物, 钙、镧、镁、锰、锌等金属氯化物的存在能有效抑制副反应的发生, 高产率地得到产物.     

Hydrogenation of Diaryl and Arylalkyl Ketones by Sodium Borohydride and Aluminum Chloride

Diaryl and arylalkyl ketones such as acetophe-none, p-methylacetophenone, propiophenone, and benzophe-none as well as diaryl and arylalkyl secondary alcohols such as 1-phenylethanol and benzhydrol were effectively hydrogenated to hydrocarbons (methylene) by NaBH₄, in combination with A1C1₃.     

The Sodium Borohydride and Sodium Cyanoborohydride Reduction of Unsymmetrically Substituted 3-Chloro-2-propeniminium Salts

A series of 3-substituted-3-chloro-2-propeniminium salts have been reacted with sodium borohydride and/or sodium cyanoborohydride to produce 1-substituted-1-chloro-3-N, N-dimethylamino-1-propenes in good yield.     

A Novel Application of Sodium Borohydride for the Regiospecific and Stereoselective Reduction of Conjugated Alkadiynes

Alkynes, when carrying an α-sulfonyl group, are shown to be stereoselectively reduced to z-alkenes using sodium borohydride under mildly basic conditions.