Investigation of azoles and azines. 75. Structure of 2-aryl-1,3-oxazine-4,6-diones in the gas phase

The mass-spectrometric fragmentation of a number of potentially tautomeric 2-aryl-1,3-oxazine-4,6-diones and model substances that fix the possible tautomeric forms was studied. The characteristic fragmentation pathways that are peculiar to one or another tautomer and the characteristic ions that make it possible to identify them in tautomeric mixtures were ascertained. It is shown that in the gas phase 2-aryl-1,3-oxazine-4,6-diones exist in mixtures of 4-hydroxy, 6-oxo, dipolar-ionic, and dicarbonyl forms; the amounts of the latter two forms increase with intensification of the electron-acceptor properties of the substituent in the para position of the benzene ring.See [1] for Communication 74.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 552–556, April, 1990.     

Study of azoles and azines. 78. Structure of 2-aryl-4,6-dioxo-1,3-thiazines in the crystalline state

For communication 77, see ref. [1].     

Synthesis of 2-aryl-4-azaindan-1,3-diones and 2-aryl-4-aza-5,6-benzindan-1,3-diones

Condensation of 2-hydroxymethylnicotinic and 2-hydroxymethylquinoline-3-carboxylic acid lactones with aromatic aldehydes in the presence of sodium methoxide gives, respectively, 2-aryl-4-azaindan-1,3-diones and 2-aryl-4-aza-5,6-benzindan-1,3-diones. Alkylation of 2-aryl-4-azaindan-1,3-diones with diazomethane gives the N-methylbetaines. According to the IR spectra, in the solid state the 4-azaindan-1,3-diones seemto have a strongly polarized enol structure.Translated from Khimiya Geterotsiklicheskikh Soedinenii, Vol. 6, No. 5, pp. 647–650, May, 1970.     

Azoles and azines

The dipole moments of 2-aryl-4-chloro-6-oxo-1,3-thiazines and 2-aryl-4-chloro-5-formyl-6-oxo-1,3-thiazines (Ar=C₆H₅, C₆H₅Cl-p, C₆H₅CH₃-p) were determined experimentally in benzene and calculated by the additive scheme with the vector method, as well as by the PPDP/2 method. Comparison of the data obtained with the calculated data showed that the formyl group is taken out of the plane of the thiazine ring.For Communication 64, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 272–275, February, 1988.     

Ring transformation of 6-methyl-3,4-dihydro-2H-1,3-oxazine-2,4-diones

Ring transformation of 6-methyl-3,4-dihydro-2H-1,3-oxazine-2,4-dione (Ia) and its N-sub-stituted derivatives, such as 3-methyl (Ib), 3-ethyl (Ic), and 3-benzyl (Id) derivatives is described. Reaction of Ia with hydrazine hydrate gave 1-amino-6-methyluracil (II), while Id reacted with hydrazine hydrate to give 3-hydroxy-5-methylpyrazole (III). Reaction of Ia,b,d with ethyl acetoacetate in ethanol in the presence of sodium ethoxide afforded ethyl 3-acetyl-6-hydroxy-4-methyl-2(1H) pyridone-5-carboxylate derivatives (IVa,b,d). On the other hand, reaction of Ib,c,d with ethyl acetoacetate in tetrahydrofuran in the presence of sodium hydride did not give IV, but gave 3-acetyl-1-alkyl-5-(N-alkylcarbamoyl)-6-hydroxy4-methyl-2(1H) pyridone (VIb,c,d). Mechanisms for the formation of compounds IV and VI are discussed.     

Furo- and thieno-fused 1,3-diazepine-4,6-diones

We report the first preparation of furo- and thieno-fused 1,3-diazepine-4,6-dione derivatives starting from ethyl 2-(2-methoxy-2-oxoethyl)-3-furancarboxylate and -thiophencarboxylate. The ester functionalities connected to the hetero-ring were converted regiospecifically into the desired amides. The ester groups attached to the methylene unit were converted into isocyanates via Curtius rearrangement. The ring-closure reaction was performed in the presence of lithium bis(trimethylsilyl)amide at room temperature to give furo- and thieno-fused diazepinone derivatives.     

Preparation of fused 1,3-oxazine-2,4-diones as potential antitumor agents

A series of indole, thiophene and pyrrole-fused 1,3-oxazine-2,4-diones, 2-methyl-1,3-oxazin-4-ones and 2-dimethylamino-1,3-oxazin-4-ones were synthesized and evaluated as antitumor agents.     

Azoles and azines: CXXVIII. Reaction of 2-aryl-4-hydroxy-6H-1,3-thiazin-6-ones with 6-bromo-4-oxo-4H-chromene-3-carbaldehyde

Russian Journal of General Chemistry -     

1,3-Dipolar cycloaddition of phthalazinium ylides to 5-arylidene-2-spirocyclohexane-1,3-dioxane-4,6-diones

Tetrahydrospiropyrrolo[2,1-a]phthalazines were synthesized by the reaction of 5-arylidene-2-spirocyclohexane-1,3-dioxane-4,6-diones with phthalazinium ylides. One of the reaction products, viz., 3-ethoxycarbonyl-2-(4-methoxyphenyl)-2′,2′-pentamethylene-1,2,3,10b-tetrahydrospiro[pyrrolo[2,1-a]phthalazine-1,5′-[1,3]dioxane]-4′,6′-dione, was studied by X-ray diffraction. The spectroscopic characteristics of the reaction products are discussed. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2362–2365, October, 2005.     

Azines and azoles. 64. Mass spectra and tautomerism of 2-aryl-4,6-dioxo-1,3-thiazines

Mass spectra of 2-aryl-4,6-dioxo-1,3-thiazines were studied and the general fragmentation paths of these compounds determined. Based on mass spectra of compounds with fixed structures, 2-aryl-5,5-dialkyl-4,6-dioxo-1,3-thiazines, 4-alkoxy- and 4-acyloxy-2-aryl-6-oxo-1,3-thiazines, the decomposition paths of the dicarbonyl and hydroxycarbonyl forms were determined. It was concluded on the basis of the obtained data that 2-aryl-4,6-dioxo-1,3-thiazines exist in the gas phase predominantly in the hydroxycarbonyl form.For Communication 63, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1409–1412, October, 1987.     

1,3-Dioxane-4,6-diones in organic synthesis (review)

Material dealing with methods for obtaining 1,3-dioxane-4,6-diones and their derivatives, methods for cleaving the 1,3-dioxane ring, and, within the framework of a synthone approach, trends in their utilization in organic synthesis is correlated.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 579–599, May, 1991.     

Vibrational and electronic spectral studies of substituted 1,3-dihydro-1,3-diphenyl-2-thioxo-2H,5H-pyrimidine-4,6-diones

The vibrational spectra of 1,3-diphenyl-; 1,3-di (4′-chlorophenyl)-; 1,3-di(3′-methoxyphenyl)-1,3-dihydro-2-thioxo-2H,5H-pyrimidine-4,6-diones in solid state (KBr pellet) and in solution (CHCl₃ and CCl₄) have been studied and assignments made. Tautomeric and hydrogen bonding behaviour are discussed. Electronic spectra in various solvents at different pH values are recorded. The effect of substituents, change of solvent on the π—π* and n—π* transitions of all the compounds is explained. The bathochromic and hypsochromic shifts observed when the neutral form changes to the cationic or anionic form depending on the pH of solution, are also discussed.     

Nitration of 2-substituted pyrimidine-4,6-diones,structure and reactivity of 5,5-gem-dinitropyrimidine-4,6-diones

Nitration of some 2-substituted pyrimidine-4,6-diones in sulfuric acid was studied, which afforded previously unknown 5,5-gem-dinitropyrimidine-4,6-diones in high yields. The gem-dinitro products were easily attacked by nucleophiles with concomitant formation of gem-dinitroacetyl derivatives, which in turn could be further hydrolyzed to salts of dinitromethane and triureas.     

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.     

Pyrimidine derivatives and related compounds. 38. Synthesis of 1,3-oxazine-2,4-diones and their reaction with nucleophiles. Ring transformation of 1,3-oxazines to pyrimidines

5,6-Unsubstituted 1,3-oxazine-2,4-diones ( 3 ) and 6-unsubstituted 5-methyl-1,3-oxazine-2,4-diones ( 4 ) were prepared by reduction of the corresponding 6-chloro derivatives ( 1 and 2 ). Treatment of 6-chloro-3-methyl-1,3-oxazine-2,4-dione ( 1a ) with sodium azide, sodium cyanide, secondary amines and aniline gave the corresponding 6-substituted compounds ( 7, 9, 10 and 11 ) while the reaction of 1a and 2a,b with primary aliphatic amines such as methylamine and ethylamine caused a ring transformation to pyrimidine ring system giving barbituric acids ( 13a-d ).     

2,2-Dimethyl-5-(5-r-2-furfurylidene)-1,3-dioxane-4,6-diones

2,2-Dimethyl-5-(5-methyl-2-furfurylidene)-1,3-dioxane-4,6-dione crystals were subjected to an x-ray diffraction study. The unit cell of the crystal contains two symmetrically independent A and B molecules that exist in the x-cis conformation, which is stabilized by conjugation between the heteroring and, possibly, an intramolecular hydrogen bond.See [1] for Communication 1.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1453–1456, November, 1988.     

Structure of azaindan-1,3-diones in solution

It is shown spectrophotometrically that 2-phenylazaindan-1,3-diones can give in solution a cation, a dipolar ion and an anion, and the protolysis constants of the forms of 2-phenyl-4-azaindan-1,3-dione and 2-phenyl-5-azaindan-1,3-dione are found.     

Diastereoselective synthesis of 6-functionalized 4-aryl-1,3-oxazinan-2-ones and their application in the synthesis of 3-aryl-1,3-aminoalcohols and 6-arylpiperidine-2,4-diones

Halocyclocarbamation of benzyl N-(1-phenyl-3-butenyl)carbamates afforded 6-functionalized 4-aryl-1,3-oxazinan-2-ones with moderate to excellent diastereoselectivity depending on the N-substituent. Importantly, in contrast to reported cyclocarbamations of homoallylic carbamates, which are generally trans-diastereoselective, cyclization of N-unsubstituted Cbz-protected homoallylamines led to cis-1,3-oxazinan-2-ones, predominantly. The use of N-benzylated and in situ prepared N-silylated derivatives resulted however in trans-selectivity. Transition states are proposed to explain the stereochemical influence of the N-substituent on the cyclocarbamations. The functionalized 1,3-oxazinan-2-ones could be further elaborated towards biologically or synthetically important 6-arylpiperidine-2,4-diones and 3-aryl-1,3-aminoalcohols.