A mild and efficient method for nucleophilic aromatic fluorination using tetrabutylammonium fluoride as fluorinating reagent

<正>Anhydrous tetrabutylammonium fluoride(TBAF_(anh).) has been found to be a highly efficient fluorinating reagent for nucleophilic aromatic fluorinations such as fluorodenitration or halogen exchange(Halex) reaction.The products were formed in high to excellent yields under surprisingly mild reaction conditions and no phenol or ether side-products were detected in these reactions.     

Fluorodenitrations using tetrabutylammonium fluoride

Fluoroaromatics are prepared in good yield under mild conditions using the tetrabutylammonium fluoride promoted fluorodenitration of nitroaromatics.     

Application of BU4N+HSO4 − as an Ionic Liquid and Acid Catalyst for Thioacetalization of Aldehydes and Ketones

A variety of carbonyl containing compounds have been successfully reacted with 1,2-ethanedithiol in a thioacetylization reaction using tetrabutylammonium hydrogensulfate as a mild and efficient catalyst. Aldehydes and ketones react with good to excellent yields under mild conditions.     

An efficient method for synthesis of phenacyl derivatives under homogeneous phase transfer catalyst condition in aqueous media

In this letter,a mild and efficient procedure for synthesis of phenacyl derivatives under homogenous catalysis in the presence of tetrabutylammonium bromide in aqueous media is described.The nucleophilic substitution reactions were performed under ecofriendly conditions and gave the corresponding products in high yields and short reaction times.     

氟代脱硝合成含氟芳香化合物

氟化四烷基铵;氟代脱硝合成含氟芳香化合物     

氟代芳香族化合物四甲基氟化铵氟代脱硝法的合成

以高活性无水四甲基氟化铵（TMAFanh.）为氟化试剂,优化反应的条件为：n(Substrate)∶n(TMAF_anh.)=1∶1.4、DMF用量为0.4 L/mol Substrate,由硝基芳烃化合物经低温氟代脱硝反应合成了含氟芳香族化合物,反应温度80~100 ℃,反应时间1~5 h,氟代产物收率19.4%~99.0%。 反应具有原料易得、工艺简单、条件温和、产物收率高和副反应少等优点。     

Facile synthesis of 2,5-diarylthiazoles via palladium-catalyzed tandem C-H substitutions. Design of tunable light emission and liquid crystalline characteristics

A mild and regioselective C-H substitution reaction of thiazole by the catalysis of the palladium/copper system is found to proceed in the presence of tetrabutylammonium fluoride under mild conditions. Applying the new reaction, we synthesized various 2,5-diarylthiazoles that exhibit light-emitting and liquid crystalline characteristics in good yields. The color of light emission is tunable by the introduction of the substituent. Differently substituted 2,5-diarylthiazoles are found to exhibit a stable liquid crystal phase in a wide temperature range.     

Practical and regioselective brominations of aromatic compounds using tetrabutylammonium peroxydisulfate

Direct bromination of wide range of aromatic compounds substituted with electron donating groups such as methoxy, hydroxy, or amino groups have been achieved with high regioselectivity by the reaction with Br₂ in the presence of tetrabutylammonium peroxydisulfate 1 under mild conditions in acetonitrile in excellent yields. The use of lithium bromide as a bromination reagent afforded high yields of monobromo compounds with complete regioselectivity under neutral and mild reaction conditions in acetonitrile.     

One-pot three-component synthesis of alpha-iminonitriles by IBX/TBAB-mediated oxidative Strecker reaction

The reaction of aldehydes, amines, and TMSCN in the presence of 2-iodoxybenzoic acid (IBX) and tetrabutylammonium bromide (TBAB) afforded alpha-iminonitriles in good to excellent yields under mild conditions. The presence of TBAB is essential for this transformation. The methodology was applied to a two-step synthesis of indolizidine via a microwave-assisted intramolecular cycloaddition of alpha-iminonitrile.     

Straightforward Synthesis of 1,2‐Dicyanoalkanes from Nitroalkenes and Silyl Cyanide Mediated by Tetrabutylammonium Fluoride

A straightforward synthesis of 1,2‐dicyanoalkanes by reacting nitroalkenes with trimethylsilyl cyanide in the presence of tetrabutylammonium fluoride is described. The reaction proceeds through a tandem double Michael addition under mild conditions. Employing the hypervalent silicate generated from trimethylsilyl cyanide and tetrabutylammonium fluoride is essential for achieving this transformation. Mechanistic studies suggest that a small amount of water included in the reaction media plays a key role. This protocol is applicable to various types of substrates including electron‐rich and electron‐deficient aromatic nitroalkenes, and aliphatic nitroalkenes. Moreover, vinyl sulfones were found to be good alternatives, particularly for electron‐deficient nitroalkenes. The broad substrate scope and functional group tolerance of the reaction makes this approach a practical method for the synthesis of valuable 1,2‐dicyanoalkanes.     

Direct Synthesis of α‐Allenols from TMS‐Protected Alkynes and Aldehydes Mediated by Tetrabutylammonium Fluoride

A unique chemoselective synthesis of α‐allenic alcohols is presented. Tetrabutylammonium fluoride (TBAF) mediated this transformation under mild reaction conditions. A range of functional groups is well‐tolerated in this reaction, while affording adducts in moderate to excellent yields (48–96 %, average 76 %). Mechanistic studies, including the use of tetrabutylammonium hydroxide (TBAH), revealed that the hydroxide ion can be the responsible for the observed rearrangement.     

Highly efficient epoxidation of electron-deficient olefins with tetrabutylammonium peroxydisulfate

The epoxidation of α,β-unsaturated carbonyl compounds such as enones and enals was efficiently achieved with tetrabutylammonium peroxydisulfate in the presence of equimolar amounts of hydrogen peroxide and NaOH in acetonitrile or methanol at 25 °C in excellent yields. Base-sensitive substrate such as cinnamaldehyde could be successfully epoxidized in short reaction time under mild reaction conditions.     

Tetrabutylammonium tribromide (TBATB) as an efficient generator of HBr for an efficient chemoselective reagent for acetalization of carbonyl compounds

Acyclic and cyclic acetals of various carbonyl compounds were obtained in excellent yields under a mild reaction condition in the presence of trialkyl orthoformate and a catalytic amount of tetrabutylammonium tribromide (TBATB) in absolute alcohol. Chemoselective acetalization of an aldehyde in the presence of ketone, unsymmetrical acetal formation, shorter reaction times, mild reaction conditions, the stability of acid-sensitive protecting groups, high efficiencies, facile isolation of the desired products, and the catalytic nature of the reagent make the present methodology a practical alternative.     

Reaction of Diazo Compounds with Difluorocarbene: An Efficient Approach towards 1,1‐Difluoroolefins

A transition‐metal‐free difluoromethylenation of diazo compounds that proceeds under mild conditions has been developed and is based on the use of TMSCF₂Br as the difluoromethylene source and tetrabutylammonium bromide (TBAB) as the promoter. The chemoselective formal carbene dimerization reaction is achieved owing to the electronic properties and the relative stability of the difluorocarbene intermediate.     

Cyclopropenium cation promoted dehydrative glycosylations using 2-deoxy- and 2,6-dideoxy-sugar donors

Dehydrative glycosylation reactions using 2-deoxy- and 2,6-dideoxy-sugar donors promoted by a combination of 3,3-dichloro-1,2-diphenylcyclopropene and tetrabutylammonium iodide (TBAI) are described. The reactions are α-selective and proceed under mild conditions at room temperature without the need for special dehydrating agents. The reaction is shown to be effective with a number of glycosyl acceptors, including those possessing acid and base sensitive functionality.     

Rational Design of a Palladium-Catalyzed C(sp) -C(sp) Cross-Coupling Reaction Inspired by Kinetic Studies

Less is More: A highly selective Pd-catalyzed C(sp) -C(sp) cross-coupling reaction between terminal alkynes and 1-bromoacetylenes has been developed. Catalyst loading is low (only 0.0001-0.01?mol?% of Pd is required) and provides products with high selectivities and good to excellent yields under mild conditions. TBAB=tetrabutylammonium bromide, TON=turnover number.     

Lewis base-promoted aldol reaction of dimethylsilyl enolates in aqueous dimethylformamide: use of calcium chloride as a Lewis base catalyst.

In the presence of CaCl2, dimethylsilyl (DMS) enolates smoothly reacted with aldehydes under mild conditions to give aldol adducts in good to high yields. The catalytic activities of various metal and tetrabutylammonium salts have revealed that CaCl2 works as a Lewis base catalyst to activate DMS enolates. The CaCl2-promoted reaction proceeded even in the presence of water or in pure water. This catalytic system was applicable to the aldol reaction with aqueous aldehydes such as formalin.     

室温离子液体中催化合成肉桂酸苄酯

研究离子液体中肉桂酸钾和氯化苄经缩合合成肉桂酸苄酯的新方法,并对多种离子液体的作用性能进行了考察.研究结果表明,离子液体中BMImBF4的催化性能最佳,但是肉桂酸苄酯的收率仍不高,只有当相转移催化剂四丁基氯化铵存在时,肉桂酸钾与溶于离子液体中的氯化苄在温和的反应条件下才可高效率地得到肉桂酸苄酯,收率可达96.5%.产物分离简单,离子液体和相转移催化剂形成的双催化体系可以稳定地循环使用5次以上.     

Tetrabutylammonium fluoride (TBAF)-catalyzed addition of substituted trialkylsilylalkynes to aldehydes, ketones, and trifluoromethyl ketones

Herein we report that tetrabutylammonium fluoride (TBAF) is a very efficient catalyst for the addition of trialkylsilylalkynes to aldehydes, ketones, and trifluoromethyl ketones in THF solvent at room temperature. The reaction conditions are mild and operationally simple, and a variety of aryl functional groups, such as chloro, trifluoromethyl, bromo, and fluoro groups, are tolerated. Impressively, using our protocol, useful CF(3)-bearing tertiary propargylic alcohols can be synthesized. Product yields are generally better than or comparable to those in the literature. 1-Phenyl-2-trimethylsilyl acetylene, trimethyl ((4-(trifluoromethyl)phenyl)ethynyl)silane, 1-trimethylsilyl-1-hexyne, and trimethyl(thiophen-3-ylethynyl)silane underwent clean conversion to their corresponding propargylic alcohols as products under our conditions. Heterocyclic carbonyl compounds, such as furan-3-carboxaldehyde, thiophene-3-carboxaldehyde, and 2-pyridyl ketone, gave good yields of propargylic alcohols.     

Tetrabutylammonium Peroxydisulfate in Organic Synthesis; VII. a Facile and Efficient Method for the Regeneration of Carbonyl Compounds from Semicarbazones by Tetrabutylammonium Peroxydisulfate

Semicarbazones of aldehydes and ketones are oxidized to the corresponding carbonyl compounds in excellent yields by tetrabutylammonium peroxydisulfate in dichlorlethane under mild conditions.