Synthesis of heterocyclic systems with a carbohydrate fragment

The reactions of levoglucosenone with urea, thiourea andN-cyano- andN-nitroguanidines result in pyrimidine systems fused with a carbohydrate fragment. In all cases, the cyclization occurs stereospecifically. The structures of different products of conversion of levoglucosenone were established on the basis of NMR and X-ray diffraction data.     

Pentachlorocyclopropane/base complexes: matrix isolation infrared spectroscopic and density functional study of C-H- - -N hydrogen bonds

Hydrogen-bonded complexes of pentachlorocyclopropane with the bases acetonitrile, ammonia, monomethylamine, and dimethylamine have been isolated and characterized for the first time in argon matrices at 16 K. Coordination of the proton of pentachlorocyclopropane (Pccp) to the electron donor (N) of the base was evidenced by red shifts of the CH stretching mode. These shifts, which range from 22 to 170 cm(-1), increase in the order CH3CN, NH3, (CH3)NH2, and (CH3)2NH. Density functional theory (DFT) calculations at the B3LYP level agree well with experiment and support the formation of 1:1 complexes of Pccp/base. Distinct changes were observed in ring modes as well as CCl and CCl2 modes. The hydrogen bond energy of the complexes varies from 2.95 to 4.22 kcal/mol and is stronger than our previously studied bromocyclopropane-ammonia complex (2.35 kcal/mol, MP2).     

Synthetic utilization of polynitroaromatic compounds. 3. Preparation of substituted dibenz[b,f][1,4]oxazepine-11(10H)-ones from 2,4,6-trinitrobenzoic acid via nucleophilic displacement of nitro groups

[Reaction: see text]. 1,3-dinitrodibenz[b,f][1,4]oxazepin-11(10H)-one, prepared by intramolecular displacement of nitro group in N-(2-hydroxyphenyl)-2,4,6-trinitrobenzamide, reacts with O- and S-nucleophiles to yield the products of mono- or bis-substitution of the nitro groups. The nitro group in position 3 is displaced first. This observation is in contrast with earlier results for the nitro-substituted benzoannulated five-membered heterocycles. This difference in reactivity is likely due to the increased steric hindrance for peri-nitro group displacement in the case of the benzoannulated seven-membered heterocycle. N-Alkylation of the nitro-substituted dibenz[b,f][1,4]oxazepin-11(10H)-ones yields analogues of a known antidepressant drug Sintamil. The structure of the products is confirmed by NOE experiments and alternative synthesis.     

Synthesis of 2-amino-5-(N-azolyl)pyrans

N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, Moscow. Translated from Khimiya Geterotsiklicheskikh. No. 12, pp, 1699–1700, December, 1995. Original article submitted November 24, 1995     

Synthetic utilization of polynitroaromatic compounds. 1. S-derivatization of 1-substituted 2,4,6-trinitrobenzenes with thiols

Reactions of 1-R-2,4,6-trinitrobenenes (R = alkyl, protected aldehyde, aminocarbonyl, cyano groups, or isoxazole ring) with thiol salts were investigated. In most cases, these reactions gave a mixture of minor para and major ortho substitution products. Reactions of N,N-disubstituted 2,4,6-trinitrobenzamides with S-,O-, and N-nucleophiles afforded products of substitution of the p-nitro group exclusively. 1-Cyano-2,4,6-trinitrobenzene was found to be the most reactive and the least selective: all three nitro groups can be substituted using an excess of thiol salts. 2-R-4, 6-dinitrobenzamides showed no regioselectivity under similar conditions to yield 1:1 mixtures of para and ortho isomers.     

Methoxy-activated indole-7-carbohydrazides; synthesis,antioxidant, and anticancer properties

Indole has been known as a key heterocyclic motif in the development of new structures for both chemical and biological properties. In this current study, a new range of indole-7-carbohydrazides has been successfully synthesized starting from the readily available 3-phenyl and 2,3-diphenyl 4,6-dimethoxyindoles. The structures of the novel compounds were confirmed by utilizing ¹H NMR, ¹³C NMR, FT-IR, high-resolution mass spectrometry, and single crystal X- ray diffraction techniques. In addition, the indole-7-carbohydrazides showed promising antioxidant results in preliminary screens. Some of the new compounds generated from dimethoxy indoles were also screened for their anticancer activity against SH-SHY5Y (human neuroblastoma), AGS (human gastric adenocarcinoma), and MDA-MB-231 (human breast adenocarcinoma) cell lines. The results revealed that the compound 12 was the promising candidate, showing cytotoxic effects on both neuroblastoma, stomach, and breast cancer cells.     

A Novel Three Dimensional Organic–Inorganic Hybrid Based Porous Phase: Synthesis and Characterization of Reduced Oxovanadium pyromellitate, [VIV2O2(H2O)2(C6H2(COO)4)]

The hydrothermal reaction of a mixture of VOSO₄ · xH₂O, 1,2,4,5-benzenetetracarboxylic acid (pyromellitic acid) and 0.1 M H₂SO₄ for 72 h at 160 °C gives blue needle like crystals of [V^IV ₂O₂(H₂O)₂(C₆H₂(COO)₄)] in 30% yield. The compound has a porous 3-D extended network structure having a rigid architecture which is held together by the multidentate functionalities of 1,2,4,5-benzenetetracarboxylate ligand. Crystal data for the compound: monoclinic space group C 2/c (No:15), a = 11.756(5) ?, b = 9.645(3) ?, c = 11.822(7) ?, β = 107.10(4)°, Z = 8. The compound constitutes the first example of a fully reduced oxovanadium based solid incorporating the organic ligand. This article consists of synthesis, crystal structure and characterization of [V^IV ₂O₂(H₂O)₂(C₆H₂(COO)₄)].     

Common fixed point theorems for families of occasionally weakly compatible mappings

We prove some common fixed point theorems in probabilistic semi-metric spaces for families of occasionally weakly compatible mappings. We also give a common fixed point theorem for mappings satisfying an integral-type implicit relation.     

Synthesis and Characterization of <Emphasis Type="Italic">Cis</Emphasis>-[V<Superscript>IV</Superscript>O(pzc)<Subscript>2</Subscript>(H<Subscript>2</Subscript>O)]·2H<Subscript>2</Subscript>O (pzc: 2-pyrazinecarboxylate)

Abstract  

Hydrothermal synthesis and the structural characterization of V(IV) complex of 2-pyrazinecarboxylate (pzc), is reported. The vanadium is in a distorted octahedral environment. Pairs of pyrazine-2-carboxylate ligands are always cis to each other. The pzc ligands do not link adjacent vanadium atom directly. The remainder of the three-dimensional network is completed by intense hydrogen bonding of uncoordinated water molecules to aqua and pzc ligands. Cis-[V^IVO(pzc)₂(H₂O)]·2H₂O, 1, was characterized by means of elemental analysis (CHNS), TGA, FT-IR, manganometric titration, bond valance sum calculations and single crystal X-ray diffraction methods. Crystal data for 1: monoclinic space group P2 ₁ /c and unit-cell parameters are a = 9.1142(5), b = 16.5822(10), c = 12.8936(7) ?, β = 131.625(3)° and Z = 4. To the best of our knowledge, cis-[V^IVO(pzc)₂(H₂O)] is reported without single crystal structure by Eugenio Garribba and his colleagues in year 2006. Herein we complete full characterization of the title complex with single crystal structure and also 1 will be the first reported example of solid vanadium complex of 2-pyrazinecarboxylates involving intense hydrogen bonding.