Organocatalytic activation of TMSCN by basic ammonium salts for efficient cyanation of aldehydes and imines

Basic ammonium salts act as highly effective catalysts for the cyanosilylation of aldehydes and in Strecker-type aminonitrile synthesis using TMSCN as cyanide source at 25 °C under extremely mild conditions, affording very good to excellent yields of silylated cyanohydrins and α-aminonitriles.     

A ruthenium-grafted hydrotalcite as a multifunctional catalyst for direct alpha-alkylation of nitriles with primary alcohols

Treatment of a hydrotacite, Mg6Al2(OH)16CO3, with an aqueous solution of RuCl3.nH2O afforded a monomeric Ru(IV) species on the surface of the hydrotalcite. This novel Ru-grafted hydrotalcite (Ru/HT) efficiently catalyzed alpha-alkylation of nitriles with primary alcohols through the cooperative catalysis between the Ru species and the surface base sites. The catalyst system could be further extended for the one-pot synthesis of alpha,alpha-dialkylated phenylacetonitriles via the base-catalyzed Michael reaction of alpha-alkylated phenylacetonitrile with activate olefins.     

Facile preparation of allenic hydroxyketones via rearrangement of propargylic alcohols

[formula: see text] Treatment of tertiary propargylic alcohols 13 with 3-diazo-2-butanone 6 and catalytic dirhodium tetraacetate in benzene gave good yields of the diastereomeric allenic hydroxyketones 14, with, in some cases, good diastereocontrol. These products are presumably formed via the [2,3]-sigmatropic rearrangement of an alpha-propargyloxy enol derivative. This reaction has been extended to the preparation of homoallylic hydroxyketones from allylic alcohols by reaction with 6 and the rhodium catalyst.     

Olefin exchange-mediated cyclopropanation of nitriles with homoallylic alcohols

We report herein olefin exchange-mediated cyclopropanation of nitriles with homoallylic alcohols. The use of homoallylic alcohols is central to the successful implementation.     

A simple one-pot procedure for the direct conversion of alcohols into alkyl nitriles using TsIm

A convenient and efficient one-pot preparation of nitriles from alcohols using N-(p-toluenesulfonyl)imidazole (TsIm) is described. In this method, treatment of alcohols with a mixture of NaCN, TsIm and triethylamine in the presence of catalytic amounts of tetra-n-butylammonium iodide (TBAI) in refluxing DMF furnishes the corresponding alkyl nitriles in good yields. This methodology is highly efficient for various structurally diverse alcohols with selectivity for ROH: 1° > 2° > 3°.     

Facile preparation of 3-acetoxycyclobutanone

3-Acetoxycyclobutanone is a versatile intermediate to access cyclobutanes with a variety of substitution patterns. Established procedures require a two step process that includes multiple distillations. We report a one-pot procedure that renders this compound readily available. Additionally, it was determined that copper plays a key role in the reaction sequence.     

Phase-transfer catalysis in the nickel-catalyzed cyanation of aryl halides

The nickel-catalyzed cyanation of aromatic halides under phase-transfer conditions is reported. Both liquid—liquid and solid—liquid techniques have been used, the former giving better yields and a higher catalyst turnover. The method provides a convenient and versatile route to aromatic nitriles.     

Copper-catalyzed direct cyanation of terminal alkynes with benzoyl cyanide

Copper-catalyzed direct cyanation of terminal alkynes is achieved using less toxic, stable and easy to handle benzoyl cyanide as a cyanide source and air as an oxidant. This protocol provides a good alternative to the preparation of 3-arylpropiolonitriles under mild condition.     

Catalytic hydroamination of furfuryl and tetrahydrofurfuryl alcohols with nitriles

Reaction of furfuryl and tetrahydrofurfuryl alcohols with nitriles over copper oxide catalysts under a hydrogen pressure of 15 atm at a temperature of 230C gives N-alkylfurfuryl- (yield 46–50%) and N-alkyl-tetrahydrofurfurylamines (49–53%), and N-alkylpiperidines (28–41%). A reaction mechanism is proposed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 23–26, January, 1988.     

Facile preparation of hierarchical porous carbons for supercapacitors by direct carbonization of potassium humate

Journal of Solid State Electrochemistry - A simple, cost-effective, and environmentally friendly strategy for the preparation of porous carbons for supercapacitors via direct carbonization of...     

Iron-catalyzed stereospecific olefin synthesis by direct coupling of alcohols and alkenes with alcohols

An efficient Fe(III)-catalyzed direct coupling of alkenes with alcohols and cross-coupling of alcohols with alcohols to give the corresponding substituted (E)-alkenes stereospecifically is demonstrated. Additionally, this reaction could be scaled up. The kinetic isotope effect (KIE) experiments indicated a typical secondary isotope effect in this process. Although benzylic alcohols were effective substrates, mild conditions, atom efficiency, environmental soundness, and stereospecificity are features that make this procedure very attractive.     

Reactions of 2,2-bis(trifluoromethyl)oxirane with alcohols under phase transfer catalysis

It was demonstrated that the reaction of 2,2-bis(trifluoromethyl)oxirane (1) with variety of alcohols could be successfully carried out under phase transfer catalysis conditions using sodium or potassium hydroxide as a base. For example, reaction of CH₃OH, C₂H₅OCH₂CH₂OH, HOCH₂CH₂OH with one or two moles of 1 in the presence of the catalyst [(C₄H₉)₄N⁺HSO₄⁻] gives the corresponding tertiary alcohols R[OCH₂C(CF₃)₂OH]_n (n=1 or 2) in 43-53% yield, along with some O[CH₂C(CF₃)₂OH]₂. Benzyl alcohol and phenol under similar conditions are less active, producing in the reaction with 1 the corresponding adducts ArOCH₂C(CF₃)₂OH in 31-35% yield. Fluorinated alcohols, such as CF₃CH₂OH, ClCF₂CH₂OH, HCF₂CF₂CH₂OH have much higher reactivity towards 1 giving ring opening products in 82-97% yield. Even in the reaction of hindered hexafluoro-iso-propanol the corresponding adduct was isolated in 43% yield. Surprisingly, the reaction of iso-propanol and epoxide 1, results in the formation of O[CH₂C(CF₃)₂OH]₂ as a major product, isolated in 56% yield. Possible mechanism for the formation of the last product was proposed.     

Ag2CO3-mediated direct functionalization of alkyl nitriles: Facile synthesis of γ-ketonitriles through nitrile alkylation of enol acetates

Direct C(sp3)-H functionalization of alkyl nitriles is a low toxic and facile route to nitrile-containing compounds. In this research, the Ag₂CO₃-mediated nitrile methylenation of enol acetates is developed to prepare γ-ketonitriles through the direct C(sp³)-H oxidative functionalization of acetonitrile. A radical pathway is proposed, and acetonitrile serves both as solvent and CN-containing radical source.     

Facile preparation of alkoxybenzoxazoles via direct SNAr on the benzoxazole ring

The synthesis of alkoxybenzoxazoles is in general quite challenging. During our investigation, we discovered that C-4 and C-7 fluoro precursors undergo S_NAr with alkoxides affording moderate to excellent yields of substituted product.     

A convenient preparation of nitriles by reaction of free sulfimide with aldehydes

Diphenyl free sulfimide was found to react readily with aldehydes affording the corresponding nitriles in high yields.     

RuCl3 anchored onto imine functionalized silica for the aerobic oxidation of benzylic alcohols under liquid phase catalysis

Abstract

RuCl₃ anchored onto imine functionalized silica has been developed as a heterogeneous catalyst for the selective oxidation of benzylic alcohols to aldehydes using molecular oxygen as an oxidant. SiO₂-RuCl₃ was found to be highly stable, passes hot filtration test successfully, and could be recycled several times without significant loss of activity. The SiO₂-RuCl₃ was characterized by Fourier Transform Infrared Spectroscopy (FTIR), Thermogavimetric Analysis (TGA), Scanning Electron Microscope (SEM), Transmission Electron Micrographs (TEM), X-Ray Diffractometry (XRD), and Atomic Absorption Spectrophotometric Analysis (AAS).     

Facile preparation of optically pure 7,7'-disubstituted BINOLs and their application in asymmetric catalysis

A family of optically pure 7,7'-disubsituted-2,2'-dihydroxy-1,1'-dinaphthyls have been conveniently prepared from easily accessible 7-alloxyl-2-naphthol by reaction sequences beginning with the asymmetric oxidative coupling and followed by key synthetic steps including deprotection, alkylation, and Suzuki coupling. Application of these binaphthols in catalytic phenylacetylene addition to aldehydes resulted in excellent enantioselectivities.