Ya. A. Levin

Ring contraction in reactions of 3-benzoylquinoxalin-2-ones with 1,2-phenylenediamines. Quinoxaline-benzoimidazole rearrangement

The reactions of 3-benzoylquinoxalin-2-one and its N(1)-alkyl derivatives with 1,2-phenylenediamines were accompanied by ring contraction as a result of the quinoxaline-benzoimidazole rearrangement giving rise to 2-benzoimidazolyl-substituted quinoxalines. The possible pathways of these reaction are discussed.

The Kornblum Reaction of α-Substituted 3-Benzyl-1,2-dihydro-2-oxoquinoxalines. Synthesis and Structure of 3-Benzoyl-2-oxo-1,2-dihydroquinoxaline

A method has been developed for the preparation of 3-benzoyl-2-oxo-1,2-dihydroquinoxaline by the reaction of 3-(α-chlorobenzyl)-1,2-dihydroquinoxaline under Kornblum reaction conditions to the corresponding α-azido derivative and then acid fission of the latter. The structure of the target ketone has been confirmed by X-ray analysis.

Fused nitrogen-containing heterocycles: III. 4-oxo-1-phenyl-4,5-dihydroimidazo [1,5-a]quinoxalines. A retrosynthetic approach

Retrosynthetic analysis of the structure of imidazo[1,5-a]quinoxalines made it possible to develop new convenient procedures for preparation of these compounds by reaction of 3-(α-chlorobenzyl)-1,2-dihydroquinoxalin-2-one with potassium thiocyanate or isocyanate as synthetic equivalent of the two-membered N-ÍC+ building blocks and by reaction of 3-(α-aminobenzyl)-1,2-dihydroquinoxalin-2-one with carbon disulfide, triethoxymethane, aromatic aldehydes, or acetic anhydride as synthetic equivalent of the one-membered RC3+ synthon.

Fused Nitrogen-Containing Heterocycles: IV. 3-Benzoyl-2-oxo-1,2-dihydroquinoxaline Hydrazones and Flavazoles Derived Therefrom

Abstract3-Benzoyl-1,2-dihydroquinoxalin-2-one reacts with hydrazine and thiosemicarbazide to give the corresponding hydrazone and thiosemicarbazone. The reaction with arylhydrazines yields 3-(α-arylazobenzylidene)-1,2,3,4-tetrahydroquinoxalin-2-ones which are tautomeric to the respective arylhydrazones. On heating in boiling acetic acid, the products of both types undergo intramolecular cyclocondensation with formation of 3-phenylpyrazolo[3,4-b]quinoxalines (3-phenylflavazoles). 3-Benzoyl-1,2-dihydroquinoxalin-2-one thiosemicarbazone gives rise to flavazole structure only in the presence of methyl 3-chloro-2-oxo-3-phenylpropionate as a trap of thiocarbamoyl moiety. The cyclization of 3-(α-hydrazonobenzyl)-1,2-dihydroquinoxalin-2-one is accompanied by formation of quinoxalyl ketone azine.

1,4-dioxins from methyl phenylchloropyruvate. Competition of the Darzens, Favorskii, and Gabriel reactions

The reaction of methyl phenylchloropyruvate with potassium phthalimide and sodium imidazolide leads to isomeric 2,5-dimethoxycarbonyl-3,6-diphenyl- and 2,6-dimethoxycarbonyl-3,5-diphenyl-1,4-dioxins.

Radical copolymerization of monovinyl derivatives of phosphorus

The reactivity ratios and rates of copolymerization with styrene, vinyl acetate and methyl acrylate have been determined for a number of esters and amides of vinyl phosphonic acid, and for vinyl phosphoric acid esters and vinyl phosphinoxides. The reactivity of phosphorus containing monomers and macroradicals is discussed. The chain transfer constants have been determined for polystyrene and polyvinylacetate radicals to phosphorus containing monomers. Relationships between the latter quantities and rates of H atom abstraction from various fragments of organophosphorus fragments are considered, as well as possible chain transfer mechanisms.

The Thermodynamic Parameters of Reactions of Phenyl Isocyanate with Methanol Associates

The thermodynamic parameters of reactions of phenyl isocyanate with methanol monomer, dimer, and trimer were calculated by the B3LYP and MP2 quantum-chemical methods. The enthalpies and entropies of transformations were found to increase as the degree of methanol association grew. An isokinetic dependence was observed for the transformations under consideration. The influence of the polarity of solvents on the Gibbs energies of these reactions was estimated.

Reactions of isomeric arylchloropyruvates and glycidates with hydrazines

Reactions of arylchloropyruvic acids esters with aryl- and hetarylhydrazines give rise to pyrazolinedione hydrazones as a result of a tandem condensation of the substituted hydrazines with arylchloropyruvates. In contrast to this process in reaction with hydrazine hydrate a ready reduction unexpectedly occurs by Kizhner-Wolff mechanism affording 3-hydroxydihydrocinnamic acid hydrazide as the principal product. The isomeric arylglycidate reacts along the same pattern.

3-Benzoylquinoxalin-2(1H)-one in the Kostanecki-Robinson Reaction. Synthesis and Structure of 2-Oxo-4-phenylpyrano[2,3-b]quinoxaline

Abstract3-Benzoylquinoxalin-2(1H)-one is cyclized with acetic anhydride in the presence of pyridine into 2-oxo-4-phenylpyrano[2,3-b]quinoxaline.

Imidazo[1,5-a]- and Thiazolo[3,4-a]quinoxalines Based on 3-(a-Thiocyanobenzyl)quinoxalin-2(1H)-one

When 3-(a-thiocyanobenzyl-2(1H)-one is heated, competing processes of [a]-annelation of the imidazole or thiazole rings occurs with formation of imidazo[1,5-a]- and thiazolo[3,4-a]quinoxalin-4(5H)-ones.