Oxidation of Alcohols to Carbonyl Compounds with Diisopropyl Azodicarboxylate Catalyzed by Nitroxyl Radicals

A nitroxyl-radical-catalyzed oxidation of alcohols using diisopropyl azodicarboxylate (DIAD) as the terminal oxidant is reported. A variety of primary and secondary alcohols including aliphatic, benzylic, and allylic alcohols are efficiently oxidized to their corresponding aldehydes and ketones without overoxidation to carboxylic acid. 1,2-Diols are oxidized to hydroxyl ketones or diketones depending on the amount of DIAD used

Oxidative Conversion of Silyl Enol Ethers to α,β-Unsaturated Ketones Employing Oxoammonium Salts

The oxidative conversion of silyl enol ethers to α,β-unsaturated ketones using a less-hindered class of oxoammonium salts (AZADO⁺BF₄^–) is described. The reaction proceeds via the ene-like addition of oxoammonium salts to silyl enol ethers

Divergent Synthesis of Polymethoxylated 4‑Aryl-2-quinolones

Polymethoxylated 4-aryl-2-quinolones were synthesized from the corresponding (<i>o</i>-amino­phenyl)­propiolates via Cu-catalyzed hydroarylation and subsequent deprotection/lactam formation. Selective iodination of the C3 position of the product followed by coupling reactions of the resulting 3-iodinated 4-aryl-2-quinolone afforded 3-substituted-4-aryl-2-quinolones. Moreover, the <i>N</i>-benzyl protecting group was successfully replaced with other polyoxygenated benzyl groups

Chemoselective Catalytic Oxidation of 1,2-Diols to α‑Hydroxy Acids Controlled by TEMPO–ClO₂ Charge-Transfer Complex

Chemoselective catalytic oxidation from 1,2-diols to α-hydroxy acids in a cat. TEMPO/cat. NaOCl/NaClO₂ system has been achieved. The use of a two-phase condition consisting of hydrophobic toluene and water suppresses the concomitant oxidative cleavage. A study of the mechanism suggests that the observed selectivity is derived from the precise solubility control of diols and hydroxy acids as well as the active species of TEMPO. Although the oxoammonium species TEMPO⁺Cl^– is hydrophilic, the active species dissolves into the organic layer by the formation of the charge-transfer (CT) complex TEMPO–ClO₂ under the reaction conditions

Correction to Highly Enantioselective Organocatalytic Oxidative Kinetic Resolution of Secondary Alcohols Using Chirally Modified AZADOs

Correction to Highly Enantioselective Organocatalytic Oxidative Kinetic Resolution of Secondary Alcohols Using Chirally Modified AZADO

Tandem Ruthenium-Catalyzed Transfer-Hydrogenative Cyclization/Intramolecular Diels–Alder Reaction of Enediynes Affording Dihydrocoumarin-Fused Polycycles

A tandem transfer-hydrogenative cyclization/intramolecular Diels–Alder reaction of enediyne substrates, containing 1,6-diyne, acrylate dienophile, and phenol tether moieties, was successfully accomplished using the combination of a cationic ruthenium complex, [CpRu­(AN)₃]­PF₆ (<b>1b</b>, Cp = η⁵-C₅H₅, AN = MeCN), as the catalyst and a Hantzsch ester as the H₂ surrogate to afford interesting dihydrocoumarin-fused polycyclic products as single diastereomers

Tandem Ruthenium-Catalyzed Transfer-Hydrogenative Cyclization/Intramolecular Diels–Alder Reaction of Enediynes Affording Dihydrocoumarin-Fused Polycycles

A tandem transfer-hydrogenative cyclization/intramolecular Diels–Alder reaction of enediyne substrates, containing 1,6-diyne, acrylate dienophile, and phenol tether moieties, was successfully accomplished using the combination of a cationic ruthenium complex, [CpRu­(AN)₃]­PF₆ (<b>1b</b>, Cp = η⁵-C₅H₅, AN = MeCN), as the catalyst and a Hantzsch ester as the H₂ surrogate to afford interesting dihydrocoumarin-fused polycyclic products as single diastereomers

Ruthenium-Catalyzed Transfer Oxygenative [2 + 2 + 1] Cycloaddition of Silyldiynes Using Nitrones as Adjustable Oxygen Atom Donors. Synthesis of Bicyclic 2‑Silylfurans

The first example of the Ru-catalyzed transfer oxygenative [2 + 2 + 1] cycloaddition of silyldiynes to produce bicyclic 2-silylfurans is described. This cyclization process was realized using nitrones as readily available and adjustable oxygen atom donors. The bicyclic silylfuran products could be used as platforms for a diverse range of functionalized furans

Ruthenium-Catalyzed Cycloisomerization of 1,6-Diynes with Styryl Terminals Leading to Indenylidene Cycloalkanes

In the presence of a neutral ruthenium catalyst, Cp*RuCl­(cod), 1,5,10-enediynes bearing a styryl terminal underwent cycloisomerization to afford exocyclic 1,3-dienes with an indenylidene moiety. The reaction mechanism is proposed on the basis of the results of control experiments and density functional calculations. The transformations of the obtained cyclization products were also investigated to demonstrate the synthetic potential of this method