Electroreductive acylation of aromatic ketones with acylimidazoles

[Reaction: see text]. The intermolecular reductive coupling of aromatic ketones with acylimidazoles was effected by electroreduction in the presence of chlorotrimethylsilane and gave alpha-trimethylsiloxy ketones and esters. The best result was obtained using Bu4NPF6 as a supporting electrolyte and a Pb cathode in THF. The alpha-trimethylsiloxy-containing products were transformed to the corresponding alpha-hydroxy ketones and esters by treatment with TBAF in THF. This method was also effective for the intramolecular reductive coupling of delta- and epsilon-keto acylimidazoles.     

Deacylation of aromatic ketones

The methyl esters of -(2,5-di-tert-butyl-3-thenoyl)propionic and -(2,5-di-tert-butyl-3-thenoyl)butyric acids are deacylated by prolonged refluxing with a mixture of hydrochloric and formic acids to form di-tert-butylthiophene and aliphatic dicarboxylic acids (succinic and glutaric acids, respectively). The same process also occurs on heating 2,5-di-tert-butyl-3-acetylthiophene under the same conditions. Practically no deacylation occurs on refluxing these thiophene derivatives with hydrochloric acid alone or with a mixture of hydrochloric acid and acetic acid. Attempts to deacylate methyl -(2,5-diethyl-3-thenoyl)propionate were unsuccessful. Assumptions regarding the peculiarities of deacylation in the 2,5-dialkyl-3-acylthiophene series associated with the geometry of the thiophene ring are expressed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 181–183, February, 1971.     

Electroreductive crossed pinacol coupling of aromatic ketones with aliphatic ketones and aldehydes

The intermolecular crossed pinacol coupling of aromatic ketones with aliphatic aldehydes and ketones was effected by electroreduction in the presence of chlorotrimethylsilane. The best result was obtained using a Pb cathode in Bu₄NPF₆/THF. The electroreduction of aromatic 1,4-, 1,5-, and 1,6-diketones under the same conditions gave four-, five-, and six-membered 1,2-diols with trans-stereoselectivity, while the reduction of these diketones with TiCl₄-Zn produced the cis-isomers of the same intramolecular crossed pinacol coupling products predominantly.     

Synthesis of aromatic polyesters by direct polycondensation with triphenylphosphine dichloride

Aromatic polyesters of high molecular weights were prepared by the direct polycondensation reaction of dicarboxylic acids and bisphenols or hydroxybenzoic acids with triphenylphosphine dichloride as a new condensing agent. Reaction conditions, including the amount of reagents and the concentration of monomer, solvent, and acid acceptor, were investigated. The aromatic polyester with the solution viscosity of 1.66 dL/g was obtained from bisphenol. A and terephthalic and isophthalic acid in quantitative yield under the optimum condition. The principal advantage of this condensing agent is that, based on the recycling system, recovered triphenylphosphine oxide can be reconverted to the reactive triphenylphosphine dichloride by treating with phosgene or oxalyl chloride.     

Solid state reaction of aromatic ketones with heteroaromatics

The solid state reactions of p-nitroacetophenone,acetyl-ferrocene with indole were catalyzed by anhydrous zinc chloride or aluminum chloride,and gave exclusively the 1:2 condensation products.The solid state condensation of aromatic ketones with l-phenyl-3-methyl-5-pyrazolone was also investigated,and the 1:1 and 2:1 condensation products were obtained.The structures of eleven new products were determined by IR,MS,1H NMR and elemental analysis.     

Facile preparation of aromatic ketones from aromatic bromides and arenes with aldehydes

Aromatic ketones were efficiently prepared in good yields by the reactions of aryl bromides with n-BuLi, followed by the reactions with aromatic aldehydes or aliphatic aldehydes and the subsequent treatment with molecular iodine and K₂CO₃, in a one-pot method. The same treatment of arenes, instead of aromatic bromides, also provided the corresponding aromatic ketones in good yields. Using these methods, various diaryl ketones and alkyl aryl ketones bearing electron-rich aromatics and electron-deficient aromatics could be prepared efficiently by a simple, transition-metal-free, and therefore environmentally benign experimental procedure.     

Electroreductive crossed hydrocoupling of aromatic ketones with enol acetates

Cathodic reduction of aromatic ketones in the presence of enol acetates afforded crossed hydrocoupling products, that is, unsymmetrical pinacols, in which the new carbon-carbon bond formation took place between the carbonyl carbon of aromatic ketones and the carbon bearing acetoxyl group in enol acetates.     

Reactions ofN-pentafluorophenylcarbonimidoyl dichloride with aromatic hydrocarbons in the presence of aluminum chloride

N-Pentafluorophenylcarbonimidoyl dichloride reacts with aromatic hydrocarbons (benzene, toluene, xylenes, and mesitylene) in the presence of AlCl₃ to give stableN-pentafluorophenylbenzimidoyl chlorides, which can further react with aromatic hydrocarbons to give azomethine derivatives. An increase in the number of methyl groups in the molecule of a hydrocarbon favors the reaction.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1605–1611, September, 1993.     

Asymmetric hydrogenation of aromatic ketones with new P-chirogenic monophosphine ligands

Novel P-chirogenic anisylphenyl-HMOP derivatives have been synthesised from (R)-2,2′-bis-(trifluoromethanesulfonyloxy)1,1′-binaphthyl. Preliminary results concerning the asymmetric hydrogenation of acetophenone and 3,5-bis(trifluoromethyl)acetophenone with Ru(II)-HMOP complexes in combination with various diamines was also tackled.     

Azoles and azines. 61. Reaction of malonyl dichloride with aromatic amides

In the reaction of malonyl dichloride with substituted -enzamides, cyclic and linear products and their mixtures form, depending on the solvent and the ratio and concentrations of reagents. When the reaction is carried out in dilute dichloroethane solution, pure 2-aryl-1,3-oxazin-4,6-diones without a substituent at C₍₅₎ are obtained in good yield. These materials are extremely unstable, and in the presence of traces of water are converted to the respective N-aroylmalonamic acids.For Communication 60, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 382–385, March, 1987.     

Ruthenium-catalyzed ortho-alkenylation of aromatic ketones with alkenes by C-H bond activation

A ruthenium-catalyzed chelation-assisted C-H bond activation of aromatic ketones and the reaction with olefins to provide Heck-type products in good to excellent yields with a high regio- and stereoselective manner is described.     

Asymmetric H-D exchange reactions of fluorinated aromatic ketones

Chiral bicyclic guanidine catalyzes the asymmetric H-D exchange reactions. Up to 30% ee was achieved. DFT calculations were employed to elucidate and explain the origin of the reaction's stereoselectivity.     

Palladium-catalyzed ortho-selective C–H bond chlorination of aromatic ketones

A palladium-catalyzed ortho-selective C–H bond chlorination reaction for the preparation of 2-chloro aromatic ketones was described. Both electron-withdrawing and electron-donating groups on the aromatic rings are well tolerated under the optimized conditions. The 2-chloro aromatic ketones obtained by our method could be applied to synthesize the derivatives of 1H-indazole or benzo[d]isoxazole.