N-甲基甲酰胺与醇的氢键相互作用

The hydrogen bonding interactions between N-methylformamide and primary, secondary, and tertiary alcohols have been studied using the FT1R spectroscopic method. The most likely association complex between alcohol and N-methylformamide is the 1:1 stoichiometric complex formed between the hydroxyl group of alcohol and the carbonyl group of N-methylformamide. The formation constant of the 1:1 complexes has been calculated using the Nash method. It appears that the primary alcohols have larger formation constant compared with the secondary and tertiary alcohols. The results showed that the proton-donating ability of the alcohols decreased in the order: primary＞secondary＞tertiary, and that the association constant increased with the increase in carbon chain of the alkyl group of alcohols.     

Asymmetric synthesis of secondary alcohols from primary alcohols via intramolecular carbenoid C-H insertion catalyzed by rhodium(II) 3-phenylcholestane-2-carboxylate

Chiral secondary alcohols may be prepared from primary alcohols via asymmetric C-H insertion reactions of alpha'-alkoxy-alpha-diazoketones catalyzed by rhodium(II)(2R,3R)-3-phenylcholestane-2-carboxylate.     

Highly enantioselective hydrogenation of aromatic-heteroaromatic ketones

Asymmetric hydrogenation of ketone 1 using trans-RuCl(2)[(R)-xylbinap][(R)-daipen] (3) as a catalyst afforded secondary alcohol 2 quantitatively and in 99.4% ee. Further exploration of the effect of the thiazole ring substitution revealed that the catalyst was highly effective for the enantioselective hydrogenation of 5-benzoyl thiazoles, which afforded corresponding alcohols in 92-99% ee. The same protocol was applicable to a variety of aromatic-heteroaromatic ketones to generate secondary alcohols in excellent enantioselectivities. [reaction: see text]     

(R)-(+)-N-methylbenzoguanidine ((R)-NMBG) catalyzed kinetic resolution of racemic secondary benzylic alcohols with free carboxylic acids by asymmetric esterification

(R)-(+)-N-Methylbenzoguanidine ((R)-NMBG) was found to function as an efficient acyl-transfer catalyst for the kinetic resolution of racemic secondary benzylic alcohols in the presence of achiral carboxylic acids and pivalic anhydride. The use of a tertiary amine in this reaction is not necessary to attain good chemical yields of the products. It was determined that diphenylacetic acid could be employed as the most suitable acyl donor for achieving a high enantioselectivity for the kinetic resolution of the racemic secondary benzylic alcohols having normal aliphatic alkyl chains at the C-1 positions. On the other hand, a less-hindered carboxylic acid, such as 3-phenylpropanoic acid, functioned as a better acyl donor for the kinetic resolution of racemic secondary benzylic alcohols having branched aliphatic alkyl chains at the C-1 positions.     

Room‐Temperature Guerbet Reaction with Unprecedented Catalytic Efficiency and Enantioselectivity

We report herein an unprecedented highly efficient Guerbet‐type reaction at room temperature (catalytic TON up to >6000). This β‐alkylation of secondary methyl carbinols with primary alcohols has significant advantage of delivering higher‐order secondary alcohols in an economical, redox‐neutral fashion. In addition, the first enantioselective Guerbet reaction has also been achieved using a commercially available chiral ruthenium complex to deliver secondary alcohols with moderate yield and up to 92 % ee. In both reactions, the use of a traceless ketone promoter proved to be beneficial for the catalytic efficiency.     

Competing reactions of secondary alcohols with sodium hypochlorite promoted by phase-transfer catalysis

With aqueous hypochlorite and a phase transfer catalyst, secondary alcohols undergo hitherto unreported free radical reactions that compete with and effectively limit traditional ketone syntheses. Product mixture profiles are determined by reactant ratios, organic cosolvent, and availability of oxygen to the system. Under argon, over half of substrate alcohols, PhCH(OH)R, are converted to benzaldehyde and free radical products through beta-scission of intermediate alkyl hypochlorites. Secondary alcohols with R containing three or more carbons also may undergo delta chlorination.     

Enantioselective oxidation of secondary alcohols at a quinohaemoprotein alcohol dehydrogenase electrode

Quinohaemoprotein alcohol dehydrogenase fromComamonas testosteroni was co-immobilized with a redox polymer (a poly(vinylpyridine) complex functionalized with osmium bis(bipyridine) chloride) on an electrode. The enzyme electrode readily oxidizes primary alcohols and secondary alcohols with maximum current densities varying between 0.43 and 0.98 A m^-2 depending on the substrate and the operation temperature. The affinity of the enzyme for aliphatic alcohols increases with the chain length of the substrate (i.e., 1-pentano1 [K_m = 0.006 mM] is a much better substrate than ethanol [K_m= 2.2 mM]). The same property is observed for secondary alcohols in the series 2-propanol (K_m = 22 mM) to 2-octano1 (K_m = 0.05 mM). The enzyme electrode is enantioselective in the oxidation of secondary alcohols. A strong preference is observed for the S-2-alcohols; the enantioselectivity increases with increasing chain length. The enantiomeric ratio (E) increases from 13 for (R,S)-2-butanol to approximately 80 for (R,S)-2-heptanol and (R,S)-2-octanol. This makes the enzyme electrode, potentially, a powerful tool for the preparation of a large range of alkanones and/or for the (kinetic) resolution of racemic alcohols.     

Synthesis of Novel Derivatives of （R）-Cysteine and Their Application in Asymmetric Reduction of Prochiral Ketones

ovel chiral β-amino alcohols containing sulfide or sulfonyl groups were synthesized from （R）-cysteine. Their chiral induction in the asymmetric borane reduction of prochiral ketones was investigated. Optically active secondary alcohols with moderate or high e. e. values were obtained, and the causes of different enantioselectivities between these two sulfur-containing chiral β-amino alcohols were researched.     

N-甲基甲酰胺与醇的氢键相互作用

Amides are used as synthetic reagents and as starting mate- rials for the preparation of insecticides and pharmaceuticals products[1]. Alcohols are industrially and scientifically important organic compounds, and their physical and chemical properties are…     

Generation and reactivity of enantiomeric (BINOLato)Ni+ complexes with chiral secondary alcohols in the gas phase

In the presence of secondary alcohols, electrospray ionization of dilute methanolic solutions of nickel(II) salts and 1,1'-bis-2-naphthol (BINOL) leads to complexes of the formal composition [(BINOLato)Ni(CH3CH(OH)R)]+ (BINOLato refers to a singly deprotonated (R)- or (S)-1,1'-bis-2-naphthol ligand; R=CH3, C2H5, n-C3H7, n-C4H9, n-C5H11, n-C6H13, c-C6H11, and C6H5). Upon collision-induced dissociation, each mass-selected nickel complex either loses the entire secondary alcohol ligand or undergoes bond activation followed by elimination of the corresponding ketone, as revealed by deuterium labeling. When enantiomeric BINOLato ligands (R or S) are combined with chiral secondary alcohols (R or S), differences in the branching ratios between these channels for the two stereoisomers of the secondary alcohols provide insight into the chiral discrimination operative in the C--H- and O--H-bond activation processes. For saturated alkan-2-ols, the chiral discrimination is low, and if any preference is observed at all, ketone elimination from the homochiral complexes (R,R and S,S) is slightly favored. In contrast, the diastereomeric (BINOLato)Ni+ complexes of 1-phenylethanol exhibit preferential ketone losses for the heterochiral systems (S,R and R,S).     

Toward the creation of NMR databases in chiral solvents: bidentate chiral NMR solvents for assignment of the absolute configuration of acyclic secondary alcohols

The absolute configuration of acyclic secondary alcohols can be established from analysis of the chemical shift behaviors of the adjacent carbons in bidentate chiral solvents (R,R)- and (S,S)-1d as formulated in the boxed illustration.     

Efficient optical resolution of secondary alkyl alcohols by chiral supramolecular hosts

A novel tunable multi-chiral supramolecular host system was developed from non-chiral dicarboxylic acid and (1R, 2R)-diphenylethylenediamine via chirality transfer, which enabled highly efficient optical resolution of secondary alkyl alcohols by simple crystallization of host compounds from alcohol solution.     

Oxo-tethered ruthenium(II) complex as a bifunctional catalyst for asymmetric transfer hydrogenation and H2 hydrogenation

Newly developed oxo-tethered Ru amido complexes (R,R)-1 and their HCl adducts (R,R)-2 exhibited excellent catalytic performance for both asymmetric transfer hydrogenation and the hydrogenation of ketonic substrates under neutral conditions without any cocatalysts to give chiral secondary alcohols with high levels of enantioselectivity.     

Synthesis of Chiral Aminophenols Based on Proline and Their Application in Enantioselective Addition of Diethylzinc to Aldehydes

Three 2-{（3R, 7aS )-1, 1-disubstituted-tetrahydro-lH-pyrrolo [ 1,2- c ] [ 1,3 ] oxazol-3-yl} phenols have been synthesized from salicylaldehyde and amino alcohols derived from L-proline, and used as ligands in enantioselective addition of diethylzinc to aldehydes, the ee values of obtained secondary alcohols were found in the range of 0-90%.     

Hydrogen bonding interaction between acrylic esters and monohydric alcohols in non-polar solvents: An FTIR study

The association between acrylic esters (methyl methacrylate, ethyl methacrylate and butyl methacrylate) and some monohydric (primary, secondary and tertiary) alcohols in non-polar solvents, viz. n-heptane, CCl4 and benzene has been investigated by means of FTIR spectroscopy. The most likely association complex between alcohol and acrylic ester is 1:1 stoichiometric complex through the hydroxyl group of alcohol and the carbonyl group of acrylic ester. The formation constant of the 1:1 complexes has been calculated using Nash method. It appears that the primary alcohols have larger formation constant than the secondary and tertiary alcohols. The results show that the proton donating power of the alcohols decreases in the order primary>secondary>tertiary and the association constant increases with the increase in carbon chain of the alkyl group of acrylic esters and alcohols. Also the results show a significant dependence of the association constant upon the solvents used. The solvent effect on the formation of hydrogen bond equilibria is discussed in terms of specific interaction between the solute and solvent.     

Hydrogen bonding interaction between N-methylformamide and alcohols

The hydrogen bonding interactions between N-methylformamide and primary, secondary, and tertiary alcohols have been studied using the FTIR spectroscopic method. The most likely association complex between alcohol and N-methylformamide is the 1:1 stoichiometric complex formed between the hydroxyl group of alcohol and the carbonyl group of N-methylformamide. The formation constant of the 1:1 complexes has been calculated using the Nash method. It appears that the primary alcohols have larger formation constant compared with the secondary and tertiary alcohols. The results showed that the proton-donating ability of the alcohols decreased in the order: primary>secondary>tertiary, and that the association constant increased with the increase in carbon chain of the alkyl group of alcohols.     

2-chloro-(4R,5R)-bis[(1R,2S,5R)-menth-1-yloxycarbonyl)]-1,3,2-dioxaphospholane: a practical chiral pool-derived reagent for determining enantiomeric purity of alcohols

2-Chloro-(4 R,5 R)-bis[(1 R,2 S,5 R)-menth-1-yloxycarbonyl)]-1,3,2-dioxaphospholane is a practical reagent for reliably determining enantiomeric purity of chiral alcohols via (31)P NMR spectroscopy. The compound is available as a crystalline solid on a 20 g scale from PCl 3 and bis[(1 R,2 S,5 R)-menth-1-yl] tartrate. It is comparatively inert toward spontaneous hydrolysis under conventional laboratory conditions but undergoes quantitative substitution of alkoxide for chloride if treated with a chiral alcohol. Nonequivalent (31)P NMR signals of diastereomeric 2-alkoxy-1,3,2-dioxophospholanes were dispersed by approximately 1.4-0.1 ppm. The associated integral ratios reflected enantiomeric purities of preweighted samples of ( R)- and ( S)-1-phenylethanol, (+)- and (-)-menthol, and a set of primary, secondary, and tertiary alcohols with a precision of +/-0.4-1.0%.     

The use ofN-alkylcarbamates in sample mapping of terpene alcohols

Carbamates (I) of terpene alcohols (e.g. menthol, borneol, citronellol, nerol, geraniol) were used to develop a method for characterization and mapping of alcohol components in complex essential oils using GC, GC-MS and GC-FTIR data and the almost quantitative reaction of the primary and secondary alcohols with isocyanates. The comparison of the data of original and derivatized samples is thus the basis for assignment of components to the primary, secondary and tertiary alcohol types (e.g. Sandalwood Oil, Rose Oil) in sample mapping procedure.The NH-deformation absorption band of (I) in vapour phase FTIR-spectroscopy at 1492–1494 cm^–1 proved to be of great use in the selective registration of derivatized alcohols in complex samples.     

Aerobic oxidation of secondary alcohols in water with ABNO/tert-butyl nitrite/KPF6 catalytic system

A green and efficient transition-metal free ABNO/tert-butyl nitrite/KPF₆-catalyzed aerobic oxidation of secondary alcohols in water has been achieved. Under the optimal reaction conditions, a number of secondary aliphatic alcohols and secondary benzylic alcohols can be converted to their corresponding ketones in excellent yields (up to 99%).     

Practical calculation of molecular acidity with the aid of a reference molecule

A set of linear free energy models are presented for determining the pK(a) values of amines, alcohols, and carboxylic acids. Models are determined from a series of pK(a) predictors, taken both from traditional natural atomic orbital analysis (NAO) and from a novel approach introduced here of using a reference molecule: an ammonium ion for amines and a hydrogen sulfide molecule for alcohols and carboxylic acids. Using these reference molecules, we calculate the barrier to proton transfer and show that a number of properties associated with the transition state are correlated with the pK(a). By considering 38 predictors, we obtain a four-variable model for amines and a three-variable model for oxygen-containing compounds. The model for amines is based on 145 compounds and has a root mean squared error (RMSE) of 0.45 and R(2) = 0.98. The oxygen set has 48 molecules: RMSE = 0.26, and R(2) = 0.993. Similar, linear, and multilinear models are constructed after separating the sets into chemically similar categories: alcohols, carboxylic acids, and primary, secondary, tertiary, and aromatic amines. This separation gives simpler models with relatively low RMSE values, where the most important predictor of the pK(a) is the difference in energy between transferring the proton from the reference molecular base to the conjugate acid from the data set.