Direct Coupling Of Alcohols Research Articles

Interfacial Reaction-Directed Green Synthesis of CeO2–MnO2 Catalysts for Imine Production through Oxidative Coupling of Alcohols and Amines

Direct oxidative coupling of alcohols with amines over cheap but efficient catalysts is a promising choice for imine formation. In this study, porous CeO2-MnO2 binary oxides were prepared via an interfacial reaction between Ce2(SO4)3 and KMnO4 at room temperature without any additives. The as-prepared porous CeO2-MnO2 catalyst has a higher fraction of Ce3+, Mn3+, and Mn4+ and contains larger surface area and more oxygen vacancies. During the oxidative coupling reaction of alcohol with amine to imine, the as-obtained CeO2-MnO2 catalyst is motivated by the above encouraging characteristics and exhibits superior catalytic activity (98% conversion and 97% selectivity) and can also work effectively under a wide scope of temperatures and substrates. The in-depth in situ DRIFTS and density functional theory (DFT) results demonstrate that there is a strong interaction between CeO2 and MnO2 in the CeO2-MnO2 catalyst, exhibiting especially a positive synergistic effect in the direct coupling of alcohol and amine reaction.

Efficient and versatile synthesis of imines from alcohols and amines over CdS-SnS2 of heterostructure under visible-light irradiation

Imines are important N-containing intermediates in organic synthesis. The photocatalytic production of specific imines through direct coupling of alcohols and amines under mild conditions has been widely explored. However, the reported processes are not practical due to negative factors such as low photocatalytic efficiency, involvement of non-stoichiometric raw materials, limited scope of substrates, and the need of additives that are not environmentally friendly. Herein, we report the synthesis of CdS-SnS2 photocatalysts with compact heterojunctions by a one-step hydrothermal method. Using air as oxidant and without the need of additive, the prepared CdS-SnS2 composites display good to excellent activity (conversion of amines up to 98% and selectivity to the corresponding imines 99.9%) for imines generation from primary amines and alcohols with different functional groups under visible light irradiation. Unlike most of the reported methods, equivalent amounts of alcohol and amine are involved in the present protocol. A reaction mechanism based on the quenching of active species is proposed. The present work offers an effective, versatile and atom-economic approach for the synthesis of imines by cross-coupling of alcohols and amines under mild conditions.

One-pot synthesis of imines by direct coupling of alcohols and amines over magnetically recoverable CdFe2O4 nanocatalyst

A magnetically recoverable CdFe2O4 nanocatalyst (MRCFNC) has been prepared by the citrate precursor method. The MRCFNC with an average particle size of 15–20 nm was found to be a highly proficient green catalyst. They are used to synthesize of imines in the liquid phase via the coupling of benzylalcohol and benzylamine. They catalyze two distinct processes, such as oxidation of benzylalcohol to benzylaldehyde followed by imine formation in a single reaction vessel. The highest yield (98%) of the desired imine was achieved while the reaction was carried out in the solvent-free system. Based on the optimized results, further experiments were conducted under solvent-free conditions. This method has a flexible scope for diverse benzylicalcohols, arylamines and the catalyst can be reused numerous times without significant loss of its catalytic proficiency.

Carbon monoliths with programmable valence bands as de novo anodes for additive-free coupling of alcohols into acetals

Designing functional and reusable electrode materials to replace homogeneous versions of scarifying additives or mediators in electrochemical organic synthesis is of great importance for both the fundamental academics and practical production of various useful compounds. Herein, we rediscover the function of nitrogen-doped carbon monoliths (NxC) as de novo anode materials to trigger a new reaction path for the synthesis of acetals from the direct coupling of alcohols without the assistance of any mediator, oxidant, acid, or organic ligand. The lowered valence bands of carbon monoliths induced by doping nitrogen are of key importance for polarizing and activating the pre-adsorbed O–H groups of benzyl alcohol molecules to boost the high Faradaic efficiency (71% at 1.8 V versus Ag/AgCl) and reusability of NxC anodes, meeting the requirements of green chemistry.

Base-controlled chemoselectivity: direct coupling of alcohols and acetonitriles to synthesise α-alkylated arylacetonitriles or acetamides

[Cp*IrCl2]2 with a phosphine-free ligand α,α,α-terpyridine shows high catalytic performance in chemodivergent synthesis of α-alkylated arylacetonitriles in the presence of K2CO3 and α-alkylated acetamides in the presence of tBuOK, respectively.

Synthesis of internal olefins by direct coupling of alcohols and olefins over Moβ zeolite

An efficient and novel Moβ zeolite catalyzed sp2-sp3 CC bond development reaction over the direct coupling of alcohols and alkenes has been performed in solvent free environment. The current method gives an attractive access to a wide variety of polysubstituted alkenes in good to excellent yields. The Moβ zeolite was effectively reused for up to 5 successive cycles.

Progress in Imine Formation from Direct Coupling of Alcohols and Amines Catalyzed by Metal Catalysts

Progress in Imine Formation from Direct Coupling of Alcohols and Amines Catalyzed by Metal Catalysts

ChemInform Abstract: Fe Powder Catalyzed Highly Efficient Synthesis of Alkenyl Halides via Direct Coupling of Alcohols and Alkynes with Aqueous HX as Exogenous Halide Sources.

Abstract A simple and efficient catalytic method for the synthesis of alkenyl halides via direct coupling of alcohols and alkynes using aqueous HX (X=Cl, Br) as halide sources has been developed under mild conditions in the presence of Fe powder (1 mol %). In comparison with the high loading of FeX3 in previously reported protocols, the present approach provides a remarkable attractive methodology to a diverse range of alkenyl halides due to the advantages of simple operation and low-level metal contamination.

Fe powder catalyzed highly efficient synthesis of alkenyl halides via direct coupling of alcohols and alkynes with aqueous HX as exogenous halide sources

A simple and efficient catalytic method for the synthesis of alkenyl halides via direct coupling of alcohols and alkynes using aqueous HX (X=Cl, Br) as halide sources has been developed under mild conditions in the presence of Fe powder (1 mol %). In comparison with the high loading of FeX3 in previously reported protocols, the present approach provides a remarkable attractive methodology to a diverse range of alkenyl halides due to the advantages of simple operation and low-level metal contamination.

The system PhIO/Ph3P as an efficient reagent for mild and direct coupling of alcohols with carboxylic acids

The PhIO/Ph3P system acts as an efficient mild reagent for the direct esterification of carboxylic acids with alcohols. (Diacyloxyiodo)benzenes, which are in situ generated in DCM solution from carboxylic acids and iodosylbenzene, react smoothly with triphenylphosphine and an alcohol at refluxing DCM in the presence of catalytic amount of DMAP to give the respective esters from good to high yields.

ChemInform Abstract: Greener Approach for the Synthesis of Substituted Alkenes by Direct Coupling of Alcohols with Styrenes Using Recyclable Broensted Acidic [NMP]+HSO4‐ Ionic Liquid

Abstractthe ionic liquid, which acts both as a catalyst and solvent, is recyclable and reusable up to 5 times with only a slight decline in yield

ChemInform Abstract: Simple and Convenient Synthesis of Fluoroalkenes via Direct Coupling of Alcohols, Alkynes and Fluoroboric Acid under Metal‐Free Conditions.

A novel and convenient method for the synthesis of fluoroalkenes from alkynes, alcohols and fluoroboric acid has been developed under mild conditions. The present protocol provides an attractive approach to access various fluoroalkenes from simple and commercially available starting materials without any metal catalyst, ligand or additive.

Simple and convenient synthesis of fluoroalkenes via direct coupling of alcohols, alkynes and fluoroboric acid under metal-free conditions

A novel and convenient method for the synthesis of fluoroalkenes from alkynes, alcohols and fluoroboric acid has been developed under mild conditions. The present protocol provides an attractive approach to access various fluoroalkenes from simple and commercially available starting materials without any metal catalyst, ligand or additive.

Direct Coupling of Cs2CO3and Alcohols for the Synthesis of Dimethyl, Diethyl, and Various Dialkyl Carbonates

Dimethyl carbonate (DMC) has been used in synthetic organic chemistry as a low-toxicity and versatile methylating and carbonylating agent. In industrial processes, DMC is widely used as a fuel additive, electrolyte for lithium ion batteries, and monomer for polycarbonate and polyurethane synthesis. Therefore, an efficient and high-yield synthesis for DMC has been actively investigated. Reaction conditions typically involve either carbon monoxide (CO) or derivatives (e.g., phosgene), or carbon dioxide (CO2) or derivatives (e.g., inorganic carbonates or organic cyclic carbonates). Due to the toxicity and flammability of CO and phosgene, the more environmentally benign and sustainable carbon sources CO2 and derivatives have been actively employed for production of DMC and related acyclic carbonates. The DMC and acyclic carbonate syntheses that have been reported include: 1) transesterification of cyclic carbonates derived from oxirane and CO2; 2) dehydrative condensation of alcohols with CO2; 3) reactions between alkyl halide and metal carbonates; 4) reactions between alcohol, alkyl halide, and CO2; and 5) reactions between alcohol and CO2 in the presence of condensing agents. Other than transesterification of cyclic carbonates, DMC is generated from alcohols or alkyl halide. In terms of chemical cost, use of an alcohol without an extra step for alkyl halide preparation appears more desirable; however, direct coupling of alcohols with CO2 or metal carbonates is challenging. In dehydrative condensation of alcohols with CO2, very efficient dehydrating reagents and metal catalysts are necessary to drive the reaction equilibrium to the product. In direct coupling of alcohols with CO2, alcohol-activation reagents such as the Mitsunobu reagent are required. According to Saito et al., dichloromethane, a common organic solvent, has been used as an alcohol-activating reagent for synthesis of various aliphatic carbonates in the presence of CO2 and Cs2CO3 (base), although synthesis of DMC has not been reported using dichloromethane. In the present study, we used dibromomethane (CH2Br2) as an alcohol-activating reagent and solvent. Using CH2Br2 and an ionic liquid, direct coupling of alcohols with Cs2CO3 in the absence of CO2 was achieved. Using Cs2CO3-mediated conditions, various aliphatic carbonates, including DMC and diethyl carbonate (DEC), were prepared with good yields. Optimization of the synthesis of carbonate 1 is summarized in Table 1. Reaction of cinnamyl alcohol and Cs2CO3 in a mixture of dichloromethane (CH2Cl2) and 1-butyl-3-methylimidazolium hexafluorophosphate (bmimPF6) was carried out at 70 C. Even in the absence of CO2, carbonate 1 was formed with 71% yield (entry 1). In this reaction, Cs2CO3

Indium(III) Catalyzed Direct sp<sup>3</sup>-sp C-C Bond Formation from Alcohols and Terminal Alkynes

A simple and efficient indium(III)-catalyzed sp3-sp C-C bond formation reaction via direct coupling of alcohols with terminal alkynes has been developed under mild conditions without any ligand, base or additive, in which both of aromatic and aliphatic alkynes and various alcohols such as benzylic, allylic and propargylic alcohols can be tolerated. This simple reaction system provides an attractive approach to a large number of internal alkynes in moderate to good yields, and only generates H2O as the side product. Keywords: sp3-sp C-C bond, alkynes, alcohols, indium(III) salts, catalytic synthesis, coupling reaction.

A novel efficient method for the synthesis of substituted olefins; cross coupling of two different alcohols using NaHSO4/SiO2

Simple and efficient cross coupling of alcohols was developed in the presence of NaHSO4/SiO2 to give the corresponding substituted olefins. Direct coupling of alcohols and alkenes was also achieved to give substituted olefins. NaHSO4/SiO2 could be recycled 7 times without loss of catalytic activity.

Efficient Fe/I 2/NaI mediated synthesis of alkenyl iodides through direct coupling of alcohols and alkynes

A new and efficient method for the synthesis of alkenyl iodides through direct coupling of alcohols and alkynes has been developed in the presence of iron powder, I 2, and NaI. This methodology not only provides an attractive approach to alkenyl iodides, but also expands the application of iron in synthetic chemistry.

Sp3‐sp2 C‐C Bond Formation via Brønsted Acid Trifluoromethanesulfonic Acid‐Catalyzed Direct Coupling Reaction of Alcohols and Alkenes

AbstractA novel and efficient trifluoromethanesulfonic acid‐catalyzed sp3‐sp2 CC bond formation reaction through the direct coupling of alcohols with alkenes has been realized under mild conditions. The present protocol provides an attractive approach to a diverse range of polysubstituted olefins in good to excellent yields with high stereo‐ and regioselectivities.

ChemInform Abstract: Iron‐Catalyzed Stereospecific Olefin Synthesis by Direct Coupling of Alcohols and Alkenes with Alcohols.

AbstractDirect coupling of benzylic alcohols with alkenes or of 2 different benzylic alcohols leads to the same type of products with complete (E)‐selectivity.

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.