A convenient synthesis of 3-alkyl-2,3-dihydro-2,4-dioxo-6-phenyl-, 3-alkyl-2,3-dihydro-4-oxo-6-phenyl-2-thioxo-, and 3-alkyl-2-arylimino-2,3-dihydro-4-oxo-6-phenyl-4H-1,3-thiazines

The reactions of 1-alkylamino-1-alkylthio-3-phenylpropene-3-thiones 3 with thiophosgene and phosgene in toluene, followed by treatment of the reaction mixture with triethylamine gave 3-alkyl-2,3-dihydro-4-oxo-6-phenyl-2-thioxo- 4 , 3-alkyl-2,3-dihydro-2,4-dioxo-6-phenyl-4H-1,3-thiazines 5 , respectively in good to excellent yields. Similarly treatment of compounds 3 with N-arylimidoyl dichloride in benzene at room temperature gave 3-alkyl-2-arylimino-2,3-dihydro-4-oxo-6-phenyl-4H-1,3-thiazines 6 in excellent yields. The reactions of compounds 3 with oxalyl chloride in toluene gave also 5 in good yields.     

3-Phenylazo-4-methyl-2,3-dihydro-1,5-benzodiazepin-2-ones

The corresponding azo derivatives, which exist primarily in the azo form, are formed in the reaction of 2,3-dihydro-1,5-benzodiazepin-2-ones with diazonium cations. The hydrazone form of these compounds is possible in solutions of acids.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1558–1560, November, 1978.     

Novel syntheses of 2,3-dihydro-1,5-benzothiazepin-4(5h)-ones and 2h-1,4-benzothiazin-3(4h)-ones

Nucleophilic additions of alpha-mercaptoalkanoate esters and beta-mercaptoalkanoate acids to benzoquinone diimines, followed by cyclization with trifluoroacetic acid or 1,3-dicyclohexylcarbodiimide (DCC), provide novel, high-yielding syntheses of 2H-1,4-benzothiazin-3(4H)-ones (3a-f) and 2,3-dihydro-1,5-benzothiazepin-4(5H)-ones (5a-c), respectively.     

1-Tetrahydrofuranyl- and 1-tetrahydropyranyl-substituted 3-hydroxy-1,6-dihydropyridazin-6-ones

The reaction of 3,6-bis(trimethylsiloxy)pyridazine and its 4,5-dihalogen-substituted derivatives with 2-chlorotetrahydrofuran and 2-chlorotetrahydropyran has given 3-hydroxy-1-(tetrahydrofuranyl- and 3-hydroxy-1-(tetrahydropyranyl)-1,6-dihydropyridazin-6-ones, the structure of which as 1-substituted derivatives has been confirmed by an investigation of their IR spectra. On the basis of a study of ionization constants, the hypothesis has been put forward that these compounds exist in the hydroxy form.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1545–1547, November, 1973.     

Synthesis and stereochemistry of 3-hydroxy-6-perfluoroalkyl-2, 3-dihydro-4-pyrones

The reaction of a number of aliphatic and alicyclic acetloxiranes with perfluoroalkanoic acid esters was studied. It is shown that substituted 3-hydroxy-6-perfluoroalkyl-2,3-dihydro-4-pyrones are formed. The reverse reaction scheme, including the formation of an intermediate -diketone and cyclization of its enol form to a dihydropyrone, was confirmed in the case of the condensation of 3-methyl-2,3-epoxycyclohexanone with ethyl trifluoroacetate. The stereochemistry of the reaction products, which exist in a half-chair confirmation with a pseudoequatorial hydroxyl group, was examined by means of PMR spectroscopy.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 897–900, July, 1978.     

3-Phenacylidene-3,4-dihydro-1H-pyrido[2,3-b]pyrazin-2-ones and 2-Phenacylidene-1,2-dihydro-4H-pyrido[2,3-b]pyrazin-3-ones

Condensation of 2,3-diaminopyridine ( 1 ) with ethyl o-, m- and p-substituted benzoylpyruvates 2–9 gave two isomeric products. The preferential formation of one or the other isomer has been achieved by different reaction conditions. All the products appear to exist in the enamine form as evidenced by their ¹H nmr and ir spectra.     

Regioselective syntheses, structural characterization, and electron ionization mass spectrometric behavior of regioisomeric 2,3-disubstituted 2-imino-1,3-thiazolidin-4-ones

The regioselective syntheses of 3-alkyl(aryl)-2-(anthracen-9'-ylimino)-1,3-thiazolidin-4-ones (2) and 2-alkyl(aryl)imino-3-(anthracen-9'-yl)-1,3-thiazolidin-4-ones (3) from N-(anthracen-9-yl)-N'-alkyl(aryl)thioureas were accomplished effectively using methyl bromoacetate and bromoacetyl bromide, respectively. Detailed structural characteristics were confirmed mainly by NMR techniques. The mass spectrometric behavior of the resulting sets of compounds of known structures was shown to be characteristic for each set. Some interesting fragmentation pathways involving the transfer and rearrangements of various moieties were also revealed, as well as regioisomerization for particular substituent-specific fragmentations.     

Synthesis of 1,6-dihydro-5-hydroxy-6-oxo-3-(trifluoromethyl)-4-pyridazinecarboxylates

The reaction of 2-(alkylamino)-3-(trifluoroacetyl)butenedioates 2a-b with alkyl and aryl hydrazines in ether provides 1,6-dihydro-6-oxo-3-(trifluoromethyl)-4-pyridazinecarboxylates as their alkylamine salts 3a-g . The structures of these products are substantiated using 2D nmr and ¹⁵N nmr techniques.     

Reactions of sulfur monochloride with some aromatic aldehyde semicarbazones and thiosemicarbazones: New syntheses of substituted 2,4-dihydro-1,2,4-triazol-3-ones, 2,4-dihydro-1,2,4-triazole-3-thiones and 2-amino-1,3,4-oxadiazoles

Treatment of various substituted semicarbazones of aromatic aldehydes with sulfur monochloride yields the corresponding substituted 2,4-dihydro-1,2,4-triazol-3-ones. With thiosemicarbazones, the products are derivatives either of the 2-amino-1,3,4 thiadiazole or of the 2,4-dihydro-1,2,4-triazole-3-thione depending on the experimental conditions.     

Microwave-assisted one-pot synthesis of 2,3-disubstituted 3H-quinazolin-4-ones

A practical synthesis of 2,3-disubstituted 3H-quinazolin-4-ones 1 with broad chemistry scope is described. The key step is the microwave promoted one-pot, two-step reaction sequence combining anthranilic acids, carboxylic acids, and amines providing efficient access to this important class of heterocycles.     

Synthesis of 4-Pyridyl-2,3-dihydro-1H-1,5-benzodiazepin-2-ones

4-Pyridyl-2,3-dihydro-1H-1,5-benzodiazepin-2-ones were obtained by the condensation of ethyl nicotinoyl- or isonicotinoylacetates with o-phenylenediamine. Alkylation of the pyridylbenzodiazepinones with ethyl iodide under phase-transfer catalysis conditions occurred at the amide nitrogen of the heterocycle, whereas in nitromethane it occurred at the nitrogen of the pyridine substituent. Bromination with N-bromosuccinimide occurred at position 3 of the heterocycle. Pyridyldibenzodiazepinones underwent thermal rearrangement to derivatives of vinylbenzimidazole.     

Formylation of 4-aryl-2,3-dihydro-1H-1,5-benzodiazepin-2-ones

The formylation of 8-chloro- and 8-methoxy-4-phenyl-2,3-dihydro-1H-1,5-benzodiazepin-2-ones with the Vilsmeier reagent leads to 3-dimethylaminomethylene derivatives which, in the case of the 8-chloro derivative, have been converted by hydrolysis in acetic acid into 8-chloro-3-formyl-4-phenyl-2,3-dihydro-1H-1,5-benzodiazepin-2-ones.Translated from Khimiya Geterotsiklicheskaya Soedinenii, No. 9, pp. 1262–1265, September, 1984.     

Synthesis of 4-styryl-2,3-dihydro-1H-1,5-benzodiazepin-2-ones

4-Styryl-2,3-dihydro-1H-1,5-benzodiazepin-2-ones were synthesized and their structure was established by means of PMR spectra and mass spectroscopy.Dnepropetrovsk State University Named in Honor of 300th Anniversary of the Reunion of Ukraina and Russia, Dnepropetrovsk 320625. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1560–1562, November, 1987.     

Chemoenzymatic synthesis of both enantiomers of 3-hydroxy-2,3-dihydro-4H-chromen-4-one

4-Oxo-3,4-dihydro-2-chromen-3-yl acetate is synthesized using manganese(III)acetate starting from 2,3-dihydro-4H-chromen-4-one. K₂CO₃ mediated hydrolysis of 4-oxo-3,4-dihdro-2-chromen-3-yl acetate furnished 3-hydroxy-2,3-dihydro-4H-chromen-4-one in high yield.The enantioselective hydrolysis of (±)-4-oxo-3,4-dihydro-2-chromen-3-yl acetate in various organic solvent-phosphate buffer (pH7) systems and enantioselective transesterification of (±)-3-hydroxy-2,3-dihydro-4H-chromen-4-one in organic solvents was investigated by screening a range of lipases. The lipase Amano PS, PPL, PLE and CCL-catalyzed asymmetric ester hydrolysis and transesterification afforded the enantiomers of 3-hydroxy-2,3-dihydro-4H-chromen-4-one and 4-oxo-3,4-dihydro-2-chromen-3-yl acetate with high enantiomeric excess (up to 97% ee) and in good yields.     

T3P catalyzed one pot three-component synthesis of 2,3-disubstituted 3H-quinazolin-4-ones

An efficient methodology for the synthesis of 2,3-disubstituted 3H-quinazolin-4-ones is described via one-pot three component reaction from anthranilic acid using T3P as catalyst. Mild reaction conditions, short reaction time, broad functional group tolerance, easy isolation of products and good yields are main advantages of this protocol.     

Manipulation of N,O-nucleophilicity: efficient formation of 4-N-substituted 2,4-dihydro-3H-1,2,4-triazolin-3-ones

A new efficient two-step synthesis of 2,4-dihydro-3H-1,2,4-triazolin-3-ones (triazolinones) from readily available amines is reported. Our novel conditions using hexamethyl disilazane, bromotrimethylsilane, and a catalytic amount of ammonium sulfate smoothly cyclize 1-formyl and 1-acetyl semicarbazides to the target triazolinones. This transformation features simultaneous manipulation of N- and O-nucleophilicity as well as differentiation of the nucleophilicity of a urea and an acyl carbonyl.