Molecular and crystal structures of 5,7-dichloro-4-nitro-2,1,3-benzoxadiazole and products of its reactions with secondary amines

The molecular and crystal structures of 5,7-dichloro-4-nitro-2,1,3-benzoxadiazole and products of its reactions with hexamethyleneimine and dimethylamine were established by X-ray diffraction analysis. The molecular structures and the systems of hydrogen bonds in the crystals of these compounds are discussed.     

Molecular and crystalline structure of the enol form of (dimorpholinophosphoryl)chloroacetaldehyde and (dimorpholinophosphoryl)-dibromomethane

The crystal and molecular structures of the products of the halogenation of the dimorpholide of ethoxyvinylphosphonic acid were determined by the method of x-ray structure analysis. It was established that (dimorpholinophosphoryl)chloroacetaldehyde only exists in the crystals as the Z-enol [(Z)-1-hydroxy-2-(dimorpholinophosphoryl)-2-chloroethene] with intra- and intermolecular H-bonds (=CH...O=P and OH...O=P). The (dimorpholinophosphoryl)dibromomethane forms centrosymmetric eight-membered cyclic dimers in the crystals due to intermolecular CH...O=P H-bonds. The structure of the morpholine and phosphoryl groups in both compounds was discussed.A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan' Scientific Center, Russian Academy of Sciences, 420083 Kazan'. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 12, pp. 2730–2737, December, 1992.     

Pfitzinger reaction of dialkyl(aryl)(2-methyl-4-oxopent-2-yl)phosphine oxides

New phosphorus-containing derivatives of quinoline-4-carboxylic acid were synthesized by the Pfitzinger reaction from isatin and dialkyl(aryl)(2-methyl-4-oxopent-2-yl)phosphine oxides.     

Dimephosphone analogues. 3. Molecular and crystal structure of dimephosphone pyridinoylhydrazones exhibiting antiphthisic activity

Molecular and crystal structures of dimephosphone nicotinoylhydrazone and dimephosphone isonicotinoylhydrazone exhibiting antiphthisic activity are studied. In contrast to aroylhydrazones of arylaldehydes, existing in the crystalline state as a mixture of two amide conformers, the studied hydrazones exist in the crystalline state in the single geometrical form E _C=N E _N-N Z _N-C(O).     

Dimephosphone analogs: II. Dialkyl(diaryl)-(2-methyl-4-oxopent-2-yl)phosphine oxide oximes: Synthesis,structure, and generation of iminoxyl radicals

Dialkyl(diaryl)-(2-methyl-4-oxopent-2-yl)phosphine oxide oximes have been synthesized for the first time. According to the X-ray diffraction data, these compounds in crystal exist as a single E isomer. Their structure in solution and the E/Z isomer ratio were determined by ¹H and ¹³C NMR spectroscopy.     

Tautomerism of Aza heterocycles: V. Structure of the spontaneous transformation products of 5-methyl-2-phenyl-3,3a,4,5,6,7-hexahydro-2H-pyrazolo-[4,3-c]pyridin-3-one in crystal and solution

5-Methyl-2-phenyl-3,3a,4,5,6,7-hexahydro-2H-pyrazolo[4,3-c]pyridin-3-one exists as zwitterion with a proton localized on the nitrogen atom of the piperidine ring and negative charge delocalized over the pyrazololate fragment. The compound is stable in crystal but ustable in solution. Its chromatographic purification and attempts to recrystallize or synthesize by condensation of phenylhydrazine with alkyl 1-methyl-4-oxopiperidin-3-carboxylate on heating in alcohols or benzene lead to the formation of a complex mixture of products. Among these products, we isolated and identified 3a,3a′-methylenebis(5-methyl-2-phenyl-3,3a,4,5,6,7-hexahydro-2H-pyrazolo[4,3-c]pyridin-3-one), 1-methyl-3-(2-phenylhydrazinylidene)pyrrolidin-2-one, and 5-methyl-2-phenyl-3,5,6,7-tetrahydro-2H-pyrazolo[4,3-c]pyridine. The structure of methyl 3-(2-phenylhydrazinylidene)-4,5-dihydro-3H-pyrrole-2-carboxylate and 3a,5-dimethyl-2-phenyl-3,3a,4,5,6,7-hexahydro-2H-pyrazolo[4,3-c]pyridin-3-one was proved by NMR spectroscopy. 3a,5-Dimethyl-2-phenyl-3,3a,4,5,6,7-hexahydro-2H-pyrazolo[4,3-c]pyridin-3-one was isolated as hydrochloride hydrate whose structure was determined by X-ray analysis.     

Structures of the products of condensation of phthalazone hydrazones with mesityl oxide

It was established on the basis of data from the UV and PMR spectra, the dipole moments, and the synthesis of fixed structures that the products of the condensation of phthalazone hydrazones with mesityl oxide have the structures of mixed phthalazone azines and mesityl oxide rather than the phthalazinylhydrazone structure that was previously assumed for them.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 678–683, May, 1981.