Synthesis of 5-and 7-fluoroquinazolin-4(1<Emphasis Type="Italic">H</Emphasis>)-ones

5-Fluoroquinazoline-2,4-diones and their 2-thio analogs were obtained from 6-fluoroanthranilic acid. Two convenient routes to 5-fluoroquinazolin-4-ones involved cyclocondensation of 6-fluoroanthranilamide with acid chlorides (anhydrides) or with aromatic (heterocyclic) aldehydes. A method for the synthesis of 7-fluoroquinazolin-4-one from 2,4-difluorobenzoic acid was proposed. Dedicated to Academician G. A. Abakumov on the occasion of his 70th birthday. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1758–1764, September, 2007.     

Ionic Liquid Promoted Eco-friendly and Efficient Synthesis of 2,3-Dihydroquinazolin-4(1<Emphasis Type="Italic">H</Emphasis>)-ones

Summary. 2,3-Dihydroquinazolin-4(1H)-ones were efficiently synthesised by the reaction of isatoic anhydride, a primary amine or ammonium acetate, and different aromatic aldehydes in 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim]BF₄) without using any acidic catalyst. Also a bis-derivative of the title compound as a polyheterocyclic system was synthesised successfully in high yield.     

Ultrasound-accelerated one-pot synthesis of <Emphasis Type="Italic">N</Emphasis>-acetyl-2-aryl-1,2-dihydro-4<Emphasis Type="Italic">H</Emphasis>-3,1-benzoxazin-4-ones

The one-pot synthesis of N-acetyl-2-aryl-1,2-dihydro-4H-3,1-benzoxazin-4-one derivatives from the condensation reaction of anthranilic acids with heteroaromatic aldehydes in the presence of excess amount of acetic anhydride has been explored. The reactions proceed smoothly under ultrasound irradiation and without catalyst at 35 − 40 °C to afford the title products in high yields.     

Ionic Liquid Promoted One-Pot Synthesis of Furo[2,3-<Emphasis Type="Italic">d</Emphasis>]pyrimidine-2,4(1<Emphasis Type="Italic">H</Emphasis>,3<Emphasis Type="Italic">H</Emphasis>)-diones

Summary. The three-component condensation of aldehyde, N,N′-dimethylbarbituric acid and alkyl or aryl isocyanide afforded the corresponding furo[2,3-d]pyrimidine-2,4(1H,3H)-diones in 1-butyl-3-methylimidazolium bromide as an ionic liquid in high yields at room temperature within several minutes.     

Synthesis of 5-alkyl-4-polyfluoroacylpyrrole-2,3(1<Emphasis Type="Italic">H</Emphasis>)-diones

Diacylation of fluoroalkyl-containing α-aminovinyl ketones with oxalyl chloride afforded 5-alkyl-4-polyfluoroacylpyrrole-2,3(1H)-diones.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2240–2242, October, 2004.     

Regiospecific O-alkylation of 4-polyfluoroalkyl-1<Emphasis Type="Italic">H</Emphasis>-pyrimidin-2-ones

The alkylation of 4-polyfluoroalkylpyrimidin-2-ones with iodomethane, 4-bromobutyl acetate, and epichlorhydrin occurs regiospecifically to form O-regioisomers.     

Structure and photochromism of 2-(<Emphasis Type="Italic">N</Emphasis>-acyl-<Emphasis Type="Italic">N</Emphasis>-arylaminomethylene)benzo[<Emphasis Type="Italic">b</Emphasis>]thiophen-3(2<Emphasis Type="Italic">H</Emphasis>)-ones

It was shown by electron absorption spectroscopy and X-ray diffraction analysis that steric strains in photochromic 2-(N-acyl-N-arylaminomethylene) benzo[b]thiophen-3(2H)-one molecules ortho-substituted in the N-phenyl ring increase the quantum yield of the N→O photoinduced rearrangement in accord with an increase in the steric constant of the ortho-substituent.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2151–2155, October, 2004.     

Transformations of 3-nitropyridin-4(1<Emphasis Type="Italic">H</Emphasis>)-one and 1-Methyl-3-nitropyridin-4(1<Emphasis Type="Italic">H</Emphasis>)-one in reaction with hydrazine

Hydrazinolysis of 3-nitropyridin-4(1H)-one and its N-methyl derivative leads to the formation of 1-(1H-pyrazol-3-yl)ethanone hydrazone whose structure was confirmed by independent synthesis from authentic 3-acetyl-1H-pyrazole and comparison of the IR and ¹H NMR spectra. Oxidation of 1-(1H-pyrazol-3- yl)ethanone hydrazone with potassium permanganate gave 1H-pyrazole-3-carboxylic acid.