Efficient CuCl-Catalyzed Selective and Direct Oxidation of β- and γ-Substituted Aliphatic Primary Alcohols to Carboxylic Acids

A new procedure for the selective and direct oxidation of aliphatic primary alcohols having substitution at β- and γ-positions to corresponding carboxylic acids was developed using a catalytic amount of ligand and additive-free CuCl with anhydrous ^t BuOOH in acetonitrile solvent under very mild reaction conditions. This procedure is very simple and mild and works efficiently without any additives at room temperature.     

β-Arylation of Racemic Secondary Benzylic Alcohols to Access Enantioenriched β-Arylated Alcohols

The transformation of alcohols into value-added products is of great importance, as simple alcohols are widespread and can be easily derived from both fossil fuels and biomass. The selective functionalization of a sp³ C−H bond on the alkyl side chain of an alcohol over its hydroxyl group would offer an expedient route to expand the chemical space of alcohols but it remains a challenging task. Harnessing the borrowing hydrogen strategy, the β-arylation of secondary alcohols with aryl bromides has been achieved in this study, which allows for the selective functionalization of a β-Csp³−H bond in an alcohol substrate. Under the catalysis of a Pd complex, secondary alcohols reacted with aryl bromides to afford 1,2-diaryl alcohols with broad substrate scope in the presence of a ketone additive. Furthermore, the enantioconvergent version of the reaction has also been realized, transforming racemic secondary alcohols into enantioenriched chiral 1,2-diaryl alcohols under the cooperative Pd and Ru catalysis. Mechanism studies indicate that the reactions are enabled by borrowing hydrogen catalysis.     

Synthesis of New F-Alkyl β-Amino Alcohols

F-alkyl oxiranes 1 and p-methylbenzene sulfonate ester intermediates 3 derived from 2-F-alkyl ethane -1,2-diols 2 are converted into F-alkyl β-amino alcohols 5 respectively by a two-step process.     

Solid Phase Synthesis of Ethyl β-Substituted Indolepropionates

A facile solid phase synthesis of ethyl β-substituted indolepropionates is reported. Condensation between indole, polymer-supported cyclic malonic acid ester and aldehyde yielded the trimolecular adducts, which was cleaved by pyridine/EtOH to release the final products in good yield with high purity.     

A General Synthesis of α-Substituted Acrylic Esters

During a study of synthetic approaches to various naturally-occurring sesquiterpenes lactones, we developed a new synthesis of the α-methylene-γ-butyrolactone group.¹ This new sequence suggested that it might be applicable to the general synthesis of α-methylenecarbonyl compounds.² This report describes the application to a general synthesis of α-substituted acrylic esters.     

Synthesis of γ-Substituted Alcohol with Polymer-bound Amide

With solid phase organic synthesis method(SPOS), polymer-bound N-enoylprolinol(4) was prepared by the attachment of N-enoylprolinol(3) to Merrifield resin and was used for asymmetric Michael additions for the first time. The enantiomeric excess obtained by this method is increased as compared with that obtained by the corresponding solution phase reactions.     

Aqueous Media Oxidation of Alcohols with Ammonium Persulfate

Oxidation of series of various primary and secondary alcohols to corresponding carbonyl compounds with ammonium persulfate in aqueous media was described. No over oxidation of primary alcohols to carboxylic acids and secondary alcohols to esters was observed. Under such conditions benzoin was converted to benzoic acid.     

A Regio-and Stereoselective Synthesis of β-Amino Alcohols

The regio-and stereoselective ring opening of epoxide with aromatic amines catalyzed by samarium trichloride and the enantioselective ring opening of cyclohexene oxide with aniline catalyzed by lanthanide complexes were studied.     

Reactions of Polyfluorinated Telomeric Alcohols with ε-Caprolactam

The possibility of preparing fluorinated oligomeric derivatives of -aminocaproic acid by reaction of polyfluorinated telomeric alcohols H(CF₂CF₂) _n CH₂OH (n = 1-4) with -caprolactam under conditions of homogeneous catalysis (triethylamine, dimethylformamide) was examined. The thermal stability of the oligomers was studied in relation to the fluorine content.     

GaI_3 Catalyzed Tetrahydropyranylation of Alcohols and Phenols

Introduction Tetrahydropyranylation is an efficient method for the protection of hydroxyl group in organic synthesis due to the stability of the tetrahydropyranyl acetals because they are stable under a variety of reaction conditions such as alkaline media, Grignard reagents, lithium al-kyls, metal hydrides, oxidative reagents, alkylating and acylating reagents.1 Tetrahydropyranyl acetals are gen-erated by a nucleophilic addition of alcohols or phenols to 3,4-dihydro-2H-pyran (DHP). A variet…     

Gal3 Catalyzed Tetrahydropyranylation of Alcohols and Phenols

In dichloromethane, the nucleophilic addition of alcohols or phenols to 3,4-dihydro-2H-pyran (DHP) was catalyzed effectively by gallium triiodide which was generated in situ by the reaction of gallium metal and iodine to give the corresponding tetrahydropyranyl acetals in good to excellent yields.     

Triphenylphosphine-Catalyzed Michael Addition of Alcohols to Acrylic Compounds

A facile triphenylphosphine-catalyzed Michael addition of alcohols to acrylic compounds was described. The reaction was carried out in open air at refluxing temperature in the presence of 10 mol% PPh3. Michael addition of saturated and unsaturated alcohols to acrylonitrile or acrylates has been examined. The reaction gave β-alkoxy derivatives with isolated yields of 5%-79%. PPh3 is cheaper and more stable than those trialkylphosphines previously used for the similar reactions, and the products can be easily separated from the reaction mixture via distillation.     

Features of the Tautomerism of Some α-Substituted Pyridines

The AM1 quantum-chemical semi-empirical method was used to calculate the values of the enthalpy of activation (H^#), the heats of reaction (H), and the tautomeric equilibrium constants (K_T) for several -substituted pyridines. It was found that the keto-enol tautomeric conversion in -pyridone occurs more readily than the amino-imino conversion in 2-aminopyridine but in 2-methylpyridine the tautomeric equilibrium does not exist at all.     

High-Performance Liquid Chromatography of α-Substituted Acetic Acid Derivatives

Abstract

Two high-performance liquid chromatographic systems for the separation of α-substituted acetic acid derivatives are presented. The first method uses a resin-based column for organic acid separations (Polypore H) with a dilute acid as mobile phase. The second system decribes the possibilities of ion-pair high-performance liquid chromatography on a reverse phase C18 column. Special attention is given to the simultaneous optimization of the counterion and buffer concentration. The applicability is demonstrated in the quality control of [1-¹¹C]-malonic acid.     

Salen-Mn(III)-Complex-Catalyzed Oxidations of Secondary Alcohols

IntroductionCarbonylgroupsarethemostimportantfunctionalgroupsinorganicsynthesis ,andtheirintroductionbyoxi dationchemistrystartingfromalcoholsisaprocessofmajorimportance .1Earlyprotocolsforthistransformationreliedontheuseofstoichiometricoxidantssuchaschromium(VI)reagentsorMnO2 .2 Withthegoalofimprovingsyn theticefficiencyandavoidingpotentialenvironmentalhaz ards ,prominentsuccessinthisdirectionhasbeenrecentlyachievedbyutilizingmolecularoxygenwithanassistanceofpotenttransitionmetalcompounds.3…     

A Mild and Efficient Oxidation of Alcohols in Water

A mild and efficient oxidation of alcohols to the corresponding carbonyl compounds using the PhI(OAc)2 (1.1 eq.) with n-Bu4NBr (8 mol %) in water at room temperature is described.This new procedure is very simple and affords the desired carbonyl compounds in high yields.     

Simultaneous gauche and Anomeric Effects in α-Substituted Sulfoxides

α-Substituted sulfoxides can experience both gauche and anomeric effects, since these compounds have the geometric requirements and strong electron donor and acceptor orbitals which are essential to make operative the hyperconjugative nature of these effects. Indeed, the title effects were calculated to take place for 1,3-oxathiane 3-oxide in polar solution, where dipolar effects are absent or at least minimized, while only the gauche effect is present in 2-fluorothiane 1-oxide. Since the fluorine atom is a suitable probe for structural analysis using NMR, the (1)J(CF) dependence on the rotation around the F-C-S═O dihedral angle of (fluoromethyl)methyl sulfoxide was evaluated; differently from 1,2-difluoroethane and fluoro(methoxy)methane, this coupling constant is at least not exclusively dependent on dipolar interactions (or on hyperconjugation). Because of the nonmonotonic behavior of the (1)J(CF) rotational profile, this coupling constant does not appear to be of significant diagnostic value for probing the conformations of α-fluoro sulfoxides.     

Microwave-assisted Oxidation of Alcohols and Polyarenes with Cetyltrimethylammonium Bromochromate

An efficient and mild methodology for oxidation of alcohols and polyarenes was described using cetyltrimethylammonium bromochromate (CTMABC) under microwave irradiation. Primary and secondary alcohols and polyarenes could be selectively oxidized under microwave irradiation into the corresponding aldehydes and ketones in high yields and short reaction time, using commercially available and magnetically retrievable oxidative material (CTMABC).