α‐Chlorination of Carboxylic Acids Using Trichloroisocyanuric Acid

Abstract

Carboxylic acids are chlorinated in the α position by heating with trichloroisocyanuric acid after formation of a small amount of the acid chloride using phosphorus trichloride.     

Preparation of N‐Chloroamides Using Trichloroisocyanuric Acid

Abstract

Amides are efficiently converted to N‐chloroamides by trichloroisocyanuric acid in methanol.     

Conversion of Alkynes into α,α-Dichloro Ketones and α,α-Dichlorodimethyl Ketals Using Trichloroisocyanuric Acid

Abstract

Trichloroisocyanuric acid reacts with alkynes in the presence of water in acetone or acetonitrile to form α,α-dichloro ketones and in methanol to form α,α-dichlorodimethyl ketals.     

An Improved Method for the Regioselective Oxidation of Stannylene Acetals and Dimerization of the α-Hydroxyketone Products

Abstract

Dibutylstannylene acetals, particularly those derived from terminal diols, were found to be oxidized regiospeeifically to α-hydroxyketones in good to excellent yield by N-bromosuccinimide. One of the products, 3-deoxy-l,2-O-isopropylidene-α-D-erythro hexofuranos-5-ulose (8), exists to about 20% in solution as a mixture of dimers. One of the dimers can be obtained as a solid and its structure was determined tentatively by a combination of NMR experiments and MM3 molecular mechanics calculations.     

Hypervalent Iodine Oxidation of Trimethylsilyl Ketene Acetals: A Convenient Route to α-Methoxylation of Esters and Lactones

Hypervalent iodine oxidation of trimethylsilyl ketene acetals of esters and lactones using iodosobenzene in methanol affords the corresponding α-methoxylated carbonyl compounds in good yields.

     

Reactions of Phosphorodiamidous Acid Esters with α-Halocarbonyl Compounds

Reactions of ethyl and tert-butyl phosphorodiamidites with chloroacetone, bromoacetone, and -chloroethyl acetate were studied. The reaction pathway is determined by the structure of the intermediate quasiphosphonium compound responsible for the formation of the Arbuzov product as well as for the occurrence of the amonalous reaction yielding vinyl phosphate.     

A Facile Synthesis of Secondary α-Alkoxy or α-Acetoxy Aromatic Ketones

Abstract: The treatment of HNIB with aromatic ketones and subsequent solvolysis using alcohol or acetic acid in one-pot system makes it possible to give corresponding secondary α-alkoxy or α-acetoxy ketones in high yields.     

Selective Oxidation of Aryl Ketones to α-Diketones with 4-Aminoperoxybenzoic Acid Supported on Silica Gel in Presence of Air

Summary. 4-Aminoperoxybenzoic acid supported on silica gel in presence of air was found to be a selective and convenient oxidant for the oxidation of methylene groups in aryl ketones to convert them to -diketones.     

Electrocatalysis of NADH Oxidation with 3,4-Dihydroxybenzoic Acid Covalently Bound to Self-assembled

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Electroanalytical Oxidation of p‐Coumaric Acid

Abstract

The mechanism of the electrochemical oxidation of p‐coumaric acid on a glassy carbon electrode was investigated using cyclic, differential pulse, and square wave voltammetry at different pHs. The oxidation of p‐coumaric acid is irreversible over the whole pH range. After successive scans, the p‐coumaric acid oxidation product deposits on the electrode surface, forming a polymeric film that undergoes reversible oxidation at a lower potential than p‐coumaric acid. This polymeric film increases in thickness with the number of scans, covering the electrode surface, and impeding the diffusion of the p‐coumaric acid and its oxidation on the electrode. The oxidation of p‐coumaric acid is pH dependent up until values close to the pK_a. For pHs higher than pK_a, the p‐coumaric acid oxidation process is pH independent. An electroanalytical determination procedure of p‐coumaric in pH 8.7 0.2 M ammonium buffer was developed, and a detection limit, LOD=83 nM, and the limit of quantification, LOQ=250 nM, were obtained.     

Oxidation of α-oxo-oximes to nitrile oxides with hypervalent iodine reagents

Upon reaction with PhI(OAc)(2), α-oxo-aldoximes are oxidized to α-oxo-nitrile oxides, while α-oxo-ketoximes are converted into nitrile oxides via the oxidative cleavage of the carbonyl-imino σ bond. The nitrile oxides thus formed were trapped with norbornene or styrene in good yield. α,α'-Dioxo-ketoximes react less efficiently.     

Organocatalytic Enantioselective Acyloin Rearrangement of α-Hydroxy Acetals to α-Alkoxy Ketones

We report an unprecedented organocatalytic enantioselective acyloin rearrangement of α,α-disubstituted α-hydroxy acetals. In the presence of a catalytic amount of chiral binol-derived N-triflyl phosphoramide, α-hydroxy acetals rearranged to α-alkoxy ketones in good to high yields with high enantioselectivities. Formation of an ion pair between the in situ generated oxocarbenium ion and the chiral phosphoramide anion was proposed to be responsible for the highly efficient transfer of chirality. Conditions for removal of cyclohexyl and cyclopentyl groups from the corresponding α-alkoxy ketones were uncovered underpinning their potential general utility as hydroxy protecting groups. Conversion of the rearranged products to the enantioenriched α-hydroxy ketone, 1,2-diol, β-amino alcohol and 1,4-dioxane was also documented.     

Oxidation of terpenoid diols with chlorine dioxide. Easy preparation of α-hydroxyketones

Oxidative dehydrogenation of vicinal diols of bornane and pinane type with chlorine dioxide in dimethylformamide has yielded α-hydroxyketones with high selectivity. 3α-Hydroxy-10β-pinane-4-one has been prepared for the first time with yield of 63–65%; the product structure has been confirmed by X-ray diffraction studies.     

Convenient One‐Pot Synthesis of Sulfonamides from Thiols using Trichloroisocyanuric Acid

A convenient synthesis of sulfonamides from thiols is described. In situ preparation of sulfonyl chlorides from thiols is accomplished by oxidation with trichloroisocyanuric acid (TCCA), benzyltrimethylammonium chloride and water (2.5 equiv). The sulfonyl chlorides are then further allowed to react with excess amine in the same reaction vessel. Triethylamine can be optionally added as acid scavenger.     

Swern Oxidation of α-Ketols to α-Diketones1

The Swern oxidation of acyclic and cyclic α-ketols delivered α-diketones or the tautomeric diosphenols in good yield.     

Homogeneous and Polymer-Supported Catalysts in the Oxidation of α-Pinene with Oxygen

The catalytic activities of nitrogen-containing cobalt complexes, polymer (AN-251 anion exchanger)-supported cobalt complex, and a polymer–salt composition containing molybdenum salt and nonionogenic water-soluble polymers were compared in the oxidation of -pinene.     

Metal–Polymer Nanocomposites with Carbon Fillers for the Catalytic Oxidation of Formic Acid

Metal–polymer Pt–Pd nanocomposites on a Nafion polymer membrane modified with carbon nanotubes and carbon black are synthesized by the chemical reduction of ions in aqueous organic solutions of reverse microemulsions. The functional characteristics of the nanocomposites are studied by cyclic voltammetry and atomic force microscopy. The synthesized nanocomposites exhibit strong catalytic activity in the formic acid oxidation reaction. It is found that, at the optimum ratio of platinum metals, the catalytic activity of the metal–polymer composites is higher than that of the carbon nanocomposites.     

Simple Method for the Preparation of Dimethyl Acetals from Ketones with Montmorillonite K 10 and p‐Toluenesulfonic Acid

A simple method for conversion of ketones to their corresponding dimethyl acetals using montmorillonite K 10 and p‐toluenesulfonic acid as acidic cocatalysts under very mild reaction conditions is described.     

Reactions of α-Formyl-α-Chlorcyclonones and γ-Butyrolactone with S-Trirnethylsilyl Ester of Dialkyldithiophosphoric Acid

Abstract

α-Formyl-α-chlorsubstituted cyclonones or α-formyl-α-chlor-γ-butyrolactone react with O,O-diizopropyltrimethylsilyldithiophosphate to give adducts which rearrange thermaly to α- dithiophos phoryl contained β-dicarbonic compounds.