Molecular Structure of Methyl 1-Isopropenyl- 5a,5b,8,8,11a-Pentamethyl-9-OXO-10-[(E)-1-Phenylmethylidene] Perhydrocyclopent [a]Chrysene-3a-Carboxylate

The molecular structure of methyl 1-isopropenyl-5a,5b,8,8,11a-pentamethyl-9-oxo-10-[(E)-1phenylmethylidene]perhydrocyclopent[a]chrysene-3a-carboxylate II is determined. Compound II C₃₈H₅₂O₃ crystallizes in the non-centrosymmetric P2₁ space group with the cell parameters: a= 11.4450(8) ?, b = 11.1995(8) ?, c = 12.5179(9) ?, β = 93.984(2)°.     

Synthesis of [1,2,4]triazolo[4,3-b]-s-tetrazines with incorporated furazan ring

Furazancarboxylic hydrazides can serve as nucleophiles to substitute for one dimethylpyrazole fragment in bis(3,5-dimethylpyrazol-1-yl)-s-tetrazine, giving the corresponding N??-[6-(3,5-dimethylpyrazol-1-yl)-s-tetrazin-3-yl]-4-R-furazan-3-carbohydrazides in good yields. Dehydration of the indicated carbohydrazides in polyphosphoric acid for the first time gave rise to [1,2,4]triazolo[4,3-b]-s-tetrazines containing the furazan ring as a substituent at the triazole ring.     

Reactions of N- and C-alkenylanilines: IX. Synthesis, oxidation, and nitration of some 7-methyl-1,3a,4,8b-tetrahydrocyclopenta[b]indoles

Heating of 4-acyl-3-iodo-7-methyl-1,2,3,3a,4,8b-hexahydrocyclopenta[b]indoles in piperidine gave 4-acyl-7-methyl-1,3a,4,8b-tetrahydrocyclopenta[b]indoles which were oxidized with KMnO4 to obtain the corresponding 4-acyl-7-methyl-1,2,3,3a,4,8b-hexahydrocyclopenta[b]indole-1,2-diols. Oxidation of 4-acyl-7-methyl-1,3a,4,8b-tetrahydrocyclopenta[b]indoles at the olefinic double bond with hydrogen peroxide in acetonitrile in the presence of formic acid afforded stereoisomeric epoxides with cis and trans orientation of the nitrogen-containing and oxirane rings. Nitration with a mixture of ammonium nitrate and trifluoroacetic anhydride produced 5-nitro derivatives. The structure of 1-{(1aR*,1bR*,6bS*,7aS*)-5-methyl-1a,1b,2,6b,7,7ahexahydrooxireno[4,5]cyclopenta[1,2-b]indol-2-yl}ethanone was determined by X-ray analysis.     

Molecular structure of 2,4-diacetyl-3-(2-chlorophenyl)-5-hydroxy-5-methyl-N-(4-methylphenyl)-1-cyclohexenylamine

The molecular structure of 2,4-diacetyl-3-(2-chlorophenyl)-5-hydroxy-5-methyl-N-(4-methylphenyl)-1-cyclohexenylamine (Ia) determined by X-ray diffractometry (XRD) is described. Two intramolecular hydrogen bonds: O-H…O=C and N-H…O=C are realized in molecule Ia.     

Conformational analysis and simulation of the structures of diisobutylsilanediol and dihydroxytetraalkyldisiloxanes and their analogs [R2(HO)Si]2X (X = CH2, S), precursors of liquid-crystalline phases

Molecular mechanics studies of structure formation in condensed phases of [R₂(HO)Si]₂X (X = CH₂ (dihydroxydicarbosilanes) and X = S (dihydroxydisilthians)) compounds have been performed and the results have been compared with those obtained for previously known columnar mesophases of [R₂(HO)Si]₂O (R = Et and Pr) (dihydroxydisiloxanes). Conformational analysis demonstrates the similarity in structure and cross-linking of dihydroxydisiloxanes and dihydroxydicarbosilanes and the difference between these compounds and dihydroxydisilthians. This allows the conclusion that for dihydroxydicarbosilanes the columnar mesophase formed by H-associates can occur. Simulation of dimeric and trimeric H-associates for (Buⁱ)₂Si(OH)₂, which belong to the same class of mesophases, has been performed.Deceased in August, 1995.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1711–1715, September, 1995.This work is supported by the International Science Foundation (Grant MP5 000).     

Thermal decomposition mechanisms of nitro-1,2,4-triazoles: A theoretical study

Possible decomposition mechanisms of C-nitro-and N-nitro-1,2,4-triazoles were simulated. We showed that in addition to the experimentally detected thermolysis products including N₂, N₂O, NO, CO₂, HCN, HNCO, 1,2,4-triazole, 3(5)-nitroso-1,2,4-triazole, and 1,2,4-triazolone, some other decompositon products (H₂O, CO, NO₂, cyanamide, cyanuric acid, and melamine) can be formed. Using the density functional approach (B3LYP/6-31G* approximation), we assessed the most favorable thermal decomposition pathways of nitrotriazoles and studied the relationships between the thermolysis pathways of these substances and their molecular and electronic structures. We found a correlation between the energy gap width (energy difference between the frontier molecular orbitals) and the stabilities of the C-nitro-1,2,4-triazole tautomers to thermal decomposition. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1338–1358, August, 2006.     

Molecular structures of methyl 4-[(1,3-dioxo-1,3-dihydro-2H-isoindol-2-yl)methyl]-1-methyl-1H-pyrazol-5-carboxylate and methyl 4-[(1,3-dioxo-1,3-dihydro-2H-isoindol-2-yl)methyl]-1-methyl-1H-pyrazol-3-carboxylate

The structure of methyl 4-[(1,3-dioxo-1,3-dihydro-2H-isoindol-2-yl)methyl]-1-methyl-1H-pyrazol-5-carboxylate is determined by X-ray crystallography and further used to elucidate the structure of methyl 4-[(1,3-dioxo-1,3-dihydro-2H-isoindol-2-yl)methyl]-1-methyl-1H-pyrazol-3-carboxylate, using the data of homo- and heteronuclear 2D NMR correlation spectroscopy.     

Synthesis,structure, and properties of new spirooxindolodibenzodiazepine derivatives

An acid-catalyzed reaction of 3-(2-aminophenylamino)-5,5-dimethylcyclohexen-1-one with isatines leads to the formation of the earlier undescribed 3,3-dimethyl-2,3,4,5,10,11-hexahydrospiro[1H-dibenzo[b,e][1,4]diazepine-11,3′-2H-indole]-1,2′-dione derivatives (6). Spiranes 6 upon heating undergo auto-redox rearrangement with disintegration to 3,3-dimethyl-1,2,3,4-tetrahydrophenazine and the corresponding oxindole. Crystals of four derivatives of compound 6 were studied by X-ray diffraction method.     

Crystal structures of copper(II) and nickel(II) complexes with 1,3-bis(3,5-di-tert-butylsalicylideneamino)propan-2-ol

Mononuclear copper(II) and nickel(II) complexes with 1,3-bis(3,5-di-tert-butylsalicylideneamino)propan-2-ol (H₃L) of the general formula [M(HL)] were obtained and structurally characterized. It was demonstrated that the presence of the tert-butyl groups precludes intermolecular hydrogen bonding in the crystals of the complexes and that their molecules are only linked by hydrophobic interactions.