Synthetic scope of Ru(OH)x/Al2O3-catalyzed hydrogen-transfer reactions: an application to reduction of allylic alcohols by a sequential process of isomerization/Meerwein-Ponndorf-Verley-type reduction

Reduction of allylic alcohols can be promoted efficiently by the supported ruthenium catalyst Ru(OH)x/Al2O3. Various allylic alcohols were converted to saturated alcohols in excellent yields by using 2-propanol without any additives. This Ru(OH)x/Al2O3-catalyzed reduction of a dienol proceeds only at the allylic double bond to afford the corresponding enol, and chemoselective isomerization and reduction can be realized under similar conditions. The catalysis is truly heterogeneous and the high catalytic performance can be maintained during at least three recycles of the Ru(OH)x/Al2O3 catalyst. The transformation of allylic alcohols to saturated alcohols consists of three sequential reactions: oxidation of allylic alcohols to alpha,beta-unsaturated carbonyl compounds; reduction of alpha,beta-unsaturated carbonyl compounds to saturated carbonyl compounds; and reduction of saturated carbonyl compounds to saturated alcohols.     

Asymmetric synthesis of cis- and trans-2,5-disubstituted pyrrolidines from 3-oxo pyrrolidine 2-phosphonates: synthesis of (+)-preussin and analogs

Pyrrolidine enones, derived from 3-oxo pyrrolidine 2-phosphonates and a HWE reaction with aldehydes, on Luche reduction give pyrrolidine allylic alcohols. The alcohols on hydrogenation (Pd/H2) give cis-2,5-disubstituted pyrrolidines and on treatment with TFA-NaBH3CN undergo a hydroxy directed reduction to trans-2,5-disubstituted pyrrolidines.     

Chiral Ferrocenyl Amino Alcohols：Preparation and Application as Catalysts in the Enantioselective Reduction of Ketones Using NaBH4／I2

Five novel chiral ferrocenyl amino alcohols were prepared from natural amino acids and used as catalysts in the asymmetric reduction of prochiral ketones with NaBH4/I2 combination.The incorporation of the ferrocenyl moiety into the molecule of the chiral amino alcohols greatly improved their enantioselectivity in the catalysis.The optically active secondary alcohols were obt5ained in moderate to good enantiomeric excesses and high chemical yields.     

Efficient addition of alcohols, amines and phenol to unactivated alkenes by Au(III) or Pd(II) stabilized by CuCl2

The nucleophilic addition of alcohols, amines and phenol to unactivated alkenes catalyzed by cationic gold and palladium becomes limited due to the fast reduction into metallic gold under reaction conditions. The presence of CuCl2 retards the reduction of Au(III) and Pd", strongly increasing the turnover number of gold and palladium catalysts. It is shown that new Au(III)-CuCl2 and Pd(II)-CuCl2 catalysts are active and selective for the nucleophilic addition of alcohols, amines and phenol to unactivated alkenes.     

Cp2TiCl2-catalyzed grignard reactions. 3. Reactions with esters: Efficient methodology for the synthesis of secondary alcohols and for the reduction of esters to primary alcohols

Cp₂TiCl₂-catalyzed Grignard reactions with esters provide general methodology for preparation of secondary alcohols or for reduction of esters to the corresponding primary alcohols.     

含流手性β-氨基醇的合成及其在对映选择性还原反应中的应用

S烷基-L-半胱氨酸2a～2c通过酯化、格林亚反应合成了光学活性含硫β-氨基 醇4a-4c，并用于潜手性酮的对映选择性NaBH_4／12还原．光学活性二级醇化学产 率很高，对映体过量最高可达93％．     

Copper‐Catalyzed Reduction of Alkyl Triflates and Iodides: An Efficient Method for the Deoxygenation of Primary and Secondary Alcohols

We describe an effective method for catalytic reduction of 1° alkyl sulfonates, and 1° and 2° iodides in the presence of a wide range of functional groups. This Cu‐catalyzed reaction provides a means for the effective deoxygenation of alcohols, as demonstrated by the highly selective reduction of 1° alcohols using a triflation/reduction sequence. A preliminary study of the reaction mechanism suggests that the reduction does not involve free‐radical intermediates.     

Highly Efficient Electroreduction of CO2 to C2+ Alcohols on Heterogeneous Dual Active Sites

Electroreduction of CO₂ to liquid fuels such as ethanol and n‐propanol, powered by renewable electricity, offers a promising strategy for controlling the global carbon balance and addressing the need for the storage of intermittent renewable energy. In this work, we discovered that the composite composed of nitrogen‐doped graphene quantum dots (NGQ) on CuO‐derived Cu nanorods (NGQ/Cu‐nr) was an outstanding electrocatalyst for the reduction of CO₂ to ethanol and n‐propanol. The Faradaic efficiency (FE) of C2+ alcohols could reach 52.4 % with a total current density of 282.1 mA cm^?2. This is the highest FE for C2+ alcohols with a commercial current density to date. Control experiments and DFT studies show that the NGQ/Cu‐nr could provide dual catalytic active sites and could stabilize the CH₂CHO intermediate to enhance the FE of alcohols significantly through further carbon protonation. The NGQ and Cu‐nr had excellent synergistic effects for accelerating the reduction of CO₂ to alcohols.     

Ce-Cu-Co/CNTs催化剂催化合成气制低碳醇及乙醇的研究

采用共浸渍法制备了不同Ce含量的Ce-Cu-Co/CNTs催化剂,考察了其在合成气制低碳醇反应中的催化性能,借助X射线衍射(XRD)、程序升温还原(H2-TPR)、N2吸脱附实验(BET)、透射电镜(TEM)和CO程序升温脱附(CO-TPD)对这些催化剂进行了表征.结果表明,当Ce的质量分数为3%时,低碳醇的时空收率和选择性达到最高,分别为696.4 mg?g-1?h-1和59.7%,其中乙醇占总醇的46.8%,适量Ce的添加能提高Cu物种在催化剂上的分散度和催化剂的还原性能,能显著地增加催化剂吸附CO的能力,促进合成醇活性位的形成,进而明显提高催化剂的活性和总醇的选择性.研究表明,将具有高活性和高碳链增长能力的CuCo基催化剂与碳纳米管的限域效应结合,可实现缩窄产物分布、大幅度提高乙醇选择性的目的.     

The stereochemistry of sodium dithionite reductions of cyclic ketones

The stereochemistry of reduction of several substituted cyclohexanones, norcamphor, and camphor by sodium dithionite (sodium hydrosulfite, Na₂S₂O₄) in aqueous DMF solution has been studied. The cyclohexanones yield mainly equatorial alcohols while the bicyclic ketones give mainly endo alcohols.     

活性炭负载的钴基催化剂催化费托合成反应一步合成C1-C18混合醇：二氧化硅助剂的作用

采用费托合成反应以及X射线衍射、H2程序升温还原、CO脉冲化学吸附和N2物理吸附表征手段研究了SiO2助剂对活性炭负载的钴基催化剂上生成C1?C18混合醇的影响。结果表明, SiO2的添加抑制了钴物种的还原,但提高了钴物种的分散度,同时抑制了金属钴颗粒在反应过程中的团聚,从而显著提高了催化剂的活性。适量SiO2的添加促进了碳化钴的生成,从而提高了总醇选择性。重要的是,通过SiO2抑制钴物种的还原,导致大量二价钴物种的生成,从而有助于CO插入到碳链中间体中而使高碳醇容易生成。     

Synthesis of dideuterated and enantiomers of monodeuterated tridecanoic acids at C-9 and C-10 positions

We report a route for the preparation of mono and dideuterated tridecanoic acids: (R)-[9-(2)H(1)]-, (S)-[9-(2)H(1)]-, (R)-[10-(2)H(1)]-, (S)-[10-(2)H(1)]-, [9,9-(2)H(2)]-, and [10, 10-(2)H(2)]-tridecanoic acids required as probes for biochemical studies on desaturases. The key intermediates in the synthesis of all these probes are ketones 9, which give rise to the corresponding alcohols 10 and 13 by reduction with LiAlD(4) and LiAlH(4), respectively. Derivatization of nondeuterated racemic alcohols 13 with (S)-(+)-9-anthranylmethoxyacetic acid ((S)-(+)-9-AMA) and chromatographic resolution of both diastereoisomers allowed us to determine the absolute configuration of the stereogenic centers by (1)H NMR using an adaptation of the model proposed by Riguera and co-workers which was validated with alcohols of known absolute configuration. Both enantiomeric alcohols (R)- and (S)-13 were recovered by reduction of each diastereomeric ester with LiAlH(4). Mesylation of alcohols 10 and 13 followed by nucleophilic substitution by LiAlD(4) generated the saturated methoxymethyl derivatives 12 and 16, respectively. Final deprotection and Jones oxidation of the resulting alcohols afforded the above deuterated tridecanoic acids.     

Spectral data of two new asymmetric sesquiterpene alcohols: (14R)-beta-oplopenol and (14S)-beta-oplopenol

The epimeric sesquiterpene alcohols (14R)-beta-oplopenol and (14S)-beta-oplopenolwere obtained by LiAlH(4) reduction of beta-oplopenone. The complete (1)H- and (13)C-NMR assignments of these two new sesquiterpene alcohols have been made using 1D and 2D NMR techniques, including COSY, NOESY, HSQC, HMBC experiments.     

Reduction of Aromatic Aldehydes and Ketones with Acyloxy Substituent at the Orthoposition by NaBH4 in the Presence of Waters*

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Enantioselective reduction of α-substituted ketones mediated by the boronate ester TarB-NO2

A facile and mild reduction procedure is reported for the preparation of chiral secondary alcohols prepared from α-substituted ketones using sodium borohydride and the chiral boronate ester (l)-TarB-NO₂. Direct reduction of substituted ketones bearing Lewis basic heteroatoms generally provided secondary alcohols of only modest enantiomeric excess likely due to either competition between the target carbonyl and the functionalized sidechains at the Lewis acidic boron atom in TarB-NO₂ or the added steric bulk of the α-sidechain. As an alternative method, these substrates were synthesized using TarB-NO₂ via a two-step procedure involving the reduction of an α-halo ketone to a chiral terminal epoxide, followed by regioselective/regiospecific epoxide opening by various nucleophiles. This procedure provides access to a variety of functionalized secondary alcohols including β-hydroxy ethers, thioethers, nitriles, and amines with enantiomeric excesses of 94% and yields up to 98%.     

A new effective route for the synthesis of substituted 2h-indazoles

A two-stage synthesis of 2H-indazoles has been established, based on consecutive reactions of reduction of 2-alkyl-, 2-cyclopropyl-, and 2-arylcarbonylazobenzenes to phenylazo-substituted benzyl alcohols and intramolecular heterocyclization of the reduction products under the influence of organic acids.     

凹凸棒石负载Cu-Fe-Co基催化剂组合体系用于CO加氢制备低碳醇

采用浸渍法(IM)和浸渍燃烧法(IMSC)制备了凹凸棒石(ATP)及凹凸棒石-多孔硅胶微球混合物(ATPS)负载CuFe-Co基改性费托催化剂,通过N_2吸附-脱附、X射线衍射(XRD)、X射线光电子能谱(XPS)、扫描电镜(SEM)、透射电镜(TEM)、H_2-程序升温还原(H_2-TPR)和CO_2-程序升温脱附(CO_2-TPD)等手段对催化剂进行了表征,并将它们应用于CO加氢制备低碳醇反应。结果表明,IMSC较IM制备催化剂更有利于CuO的负载、分散和还原,促进H_2和CO与Cu活性位的接触,但两者的最佳低碳醇合成温度均为280℃。通过对ATP和ATPS负载Cu-Fe-Co基催化剂(CFCK/ATP、CFCK/ATPS)与Cu/ZnO/Al_2O_3(CZA)甲醇催化剂的组合体系的优化,获得较理想的低碳醇合成催化剂组合体系CZA║CFCK/ATPS-IMSC。利用它们之间的"产物转化耦合效应",实现CO转化率为46.3%,低碳醇选择性为39.6%,C_(2+)醇含量为22.7%。     

Conformational analysis and stereochemistry of the reduction of 2-alkoxymethyl-4-oxopiperidines

The isomer with an axially oriented alkoxymethyl group predominates in the equilibrium mixture of 1-aklyl-2,5-dimethyl-2-alkoxymethyl-4-piperidones investigated under both alkaline and acidic equilibrium conditions, and its percentage increases as the volume of the alkoxy group increases in the order Me, Et, iso-Pr. The reduction of 4-ketopiperidines that contain a polar function in the 2 position follows the same principles as those that obtain when it is absent, i.e., exclusively the equatorial alcohols are obtained in the case of reduction with lithium and ethanol in liquid ammonia, whereas primarily the axial alcohols are obtained in the case of reduction with sodium borohydride. The selectivity of the reduction increases on passing from the free bases to the hydrochlorides.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 503–506, April, 1979.     

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.     

Transport and co-transport of carboxylate ions and alcohols in cation exchange membranes

Understanding multi-component transport behavior through hydrated dense membranes is of interest for numerous applications. For the particular case of photoelectrochemical CO₂ reduction cells (PEC-CRC), it is important to understand the multi-component transport behavior of CO₂ electrochemical reduction products including mobile carboxylates (formate and acetate) and alcohols (methanol and ethanol) in the ion exchange membranes as one role of the membrane in these devices is to minimize the permeation of these CO₂ reduction products to the anolyte as they often oxidize back to CO₂. Cation exchange membranes (CEM) are promising candidates for such devices as they act to minimize the permeation of mobile anions, such as carboxylates. However, the design of new CEMs is necessary as the permeation of carboxylates often increases in co-permeation with alcohols. Here, we investigate the transport behavior of carboxylates and alcohols in two types of CEMs (1) a crosslinked CEM was prepared by free-radical copolymerization of a sulfonated monomer (AMPS) with a crosslinker (PEGDA), and (2) Nafion® 117. We observe an increase in both PEGDA-AMPS and Nafion® 117 diffusivities to carboxylates in co-diffusion with alcohols. We attribute this behavior to charge screening by co-diffusing alcohol that reduces the electrostatic repulsion between bound sulfonates and mobile carboxylates.