α-Dimethylaminomethylene-γ-thiobutyrolactone and synthesis of heterocyclic derivatives

By the interaction of -thiobutyrolactone with bis(dimethylamino)-tert-butoxymethane, -dimethylamino-methylene--thiobutyrolactone has been obtained. Its reactions with arylhydrazines have been investigated. With phenylhydrazine, 4-(2-mercaptoethyl)-1 phenylpyrazolone-5 is formed; but with -substituted phenylhydrazines, as a result of the Fischer reaction and expansion of the thiolactone ring, 9-substituted 4, 9dihydrothiopyrano[3,4-bjindol-1(3H)-ones are formed. Analogous reactions with 1-amino derivatives of tetrahydroquinoline and tetrahydroquinaldine lead to the formation of 5, 6,10,11-tetrahydro-4H, 8H-thiopyruno(4,3:4,5jpyrrolo[3,2,1-ijlquinolin-8-ones, representatives of a new heterocyclic system.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 180–185, February, 1996.     

Synthesis and aminomethylation of some heterocyclic α-nitroxyalkyl NH acids

The recently discovered synthetic route to quaternary ammonium salts of a new series via N-aminometylation of 4,4-bis(nitroxymethyl)oxazolidin-2-one was extended to other NH acids obtained for the first time by O-nitration of known a-hydroxyalkyl derivatives of 4-methyloxazolidin-2-one, pyrrolidin-2-one, and benzimidazole. In the aminomethylation of these NH acids, dimethylamine and morpholine were used as the amine components.     

Practical synthesis of β-acyl and β-alkoxycarbonyl heterocyclic sulfones

A short and efficient synthesis for β-acyl and β-alkoxycarbonyl heterocyclic sulfones containing benzothiazol (BT) and phenyltetrazol (PT) heterocyclic core is presented here. The method seems to be general and provides the desired C-nucleophiles in very good to excellent yields from readily available starting materials.     

Quantum chemical study of α-diazocarbonyl bullvalene derivatives and related heterocyclic compounds

According to the results of PBE0/cc-pVTZ quantum chemical calculations, the equilibrium mixture of α-diazocarbonyl bullvalene derivatives (C₁₀H₈N₂O) contains an impurity of the corresponding bullvaleno-[1,2,3]oxadiazoles. The carbonyl group in the major tautomer is conjugated with the three-membered ring. The concentration of other tautomers in the equilibrium mixture of two bullvaleno[1,2,3]selenadiazoles is negligible.     

Energetic studies of two oxygen heterocyclic compounds Xanthone and tetrahydro-γ-pyrone

The present work reports an experimental thermochemical study supported by state of the art calculations of two heterocyclic compounds containing oxygen in the ring: xanthone and tetrahydro-γ-pyrone. The standard (po = 0.1 MPa) molar enthalpies of formation in the condensed phase, at T = 298.15 K, were derived from the measurements of the standard molar energies of combustion in oxygen atmosphere, using a static bomb calorimeter. The standard molar enthalpies of sublimation or vaporization, at T = 298.15 K, of the title compounds were obtained from Calvet microcalorimetry measurements. These values were used to derive the standard enthalpies of formation of the compounds in the gas-phase at the same temperature, which were compared with estimated data from G3(MP2)//B3LYP computations.     

Synthesis of 7-O-β-D-glucopyranosides of isoflavones and their heterocyclic analogues

The products of the interaction of -acetobromoglucose with 2,4,5-trihydroxyphenyl benzyl ketone and 2,4-dihydroxyphenyl 4-hydroxybenzyl ketone and also with their heterocyclic analogues, which are present completely or partially in the enolic form, have been investigated. It has been shown that in this reaction a tetra-O-acetylglucosyl residue is added at the 4-OH hydroxy group of the phenyl residue of the ketone. The compounds obtained have been converted into isoflavone 7-O-glucosides by the action of the vilsmeier reagent or acetoformic anhydride.Taras Shevchenko Kiev University. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 220–227, March–April, 1993.     

Synthesis and antitumor activity of heterocyclic acid ester derivatives of 20S-camptothecins

A series of heterocyclic acid esters of camptothecins as new compounds had been synthesized by acylation method,their in vitro and in vivo antitumor activities were evaluated.The cytotoxic results showed that 6 possessed the best efficacy on six human cancer cell lines in the six classes of CPTs' derivatives.In vivo testing results indicated that 9 had better antitumor activity against mouse liver carcinoma H_(22) than topotecan.     

Electrochemical studies and semiempirical calculations on π-conjugated dienones and heterocyclic nitrogen containing donor ligand molecules

Reduction potentials for the first electron transfer to a broad selection of nitrogen containing bi- and polydentate molecules considered as potential ligands have been determined. Results are compared with data obtained with semiempirical and UV-Vis spectroscopic data. Close correlations for the investigated molecules are observed. Systematic differences in properties of molecules with and without the keto moiety can be explained by invoking molecular orbital and surface interaction arguments. Similar structural arguments can be used to explain the behaviour of 2,4,6-tripyridin-2–yl[1,3,5]triazine. UV-Vis data match closely those derived from HOMO-LUMO calculations for these molecules.

Manganese(III) Schiff-base complexes involving heterocyclic β-diketone and diethylene triamine

Synthesis, spectral, thermal and coordination aspects of pentadentate Schiff-base complexes of the type [Mn(L)(X)] · H₂O [where H₂L = N,N′–diethylamine bis(1-phenyl-3-methyl-4-acetylimino-2-pyrazoline-5-ol) and X=NCS, NO₃, ClO₄, CN or N₃] are reported. The Schiff-base ligand (H₂L) and metal complexes have been characterized by elemental analysis, FT-IR, ¹H-NMR, magnetic measurements, molar conductivity measurements, electronic spectra, cyclic voltammetric and thermal studies. Magnetic moment values are close to 4.9 B.M. indicating high spin complexes lacking exchange interaction. Infrared spectral data suggest coordination of the secondary amino group making the ligand pentadentate. All complexes are electrochemically inactive, indicating high stability. Thermal decomposition of the Schiff-base complexes indicates loss of water of hydration and decomposition of the ligand. Kinetic parameters such as order of reaction (n) and the energy of activation (E _a) are reported using the Horowitz–Metzger method, indicating first order kinetics and giving the activation entropy (ΔS*), the activation enthalpy (ΔH*) and the free energy of activation (ΔG*).     

Steric-switched defluorofunctionalization selectivity: controlled synthesis of monofluoroalkene-masked medium-sized heterocyclic lactams and lactones

The steric-switched ipso-defluoroamination-triggered and ipso-defluorooxylation-triggered cyclization of(trifluoromethyl)alkenes with amino alcohols and diamines are achieved under mild conditions. This regioselective strategy distinguishes the different nucleophilic heteroatom sites in amino alcohols and unsymmetric diamines by the sequential defluorinative functionalization of two C(sp³)–F bonds in a CF₃ group. Various attractive monofluoroalkene-masked medium-sized heterocyclic lactams and lactones are obtained in moderate to excellent yields. Simple derivation of these masked-heterocycles efficiently affords useful skeletons of lactams, lactones, and 1,4-oxazepanes in a single diastereoisomer. Mechanism studies indicate that a unique sequential ipso-/γ-selective defluorinative functionalization pathway is involved in these transformations.     

Estimation of σ- and π-donor properties of heterocyclic thioamides by spectroscopic and magnetic resonance methods

The charge-transfer complexes (CTC) of few thioamide: 1-methylimidazoline-2-thione (MMI), 3-methyl-1-ethoxycarbonilimidazoline-2-thione (Carb), 5-methylbenzimidazoline-2-thione (BIZ), benzothiazoline-2-thione (BTZ), benzoxazoline-2-thione (BOZ) as σ-donors and diiodine as σ-acceptor were studied by spectroscopic methods (UV/Vis, (1)H NMR). CTC formation constants of thioamides with diiodine were determined using the function of the average-iodine number. The charge-transfer complexes of thioamides as π-donors with tetracyanoethylene (TCNE) as π-electron acceptor, were studied by UV-spectroscopy in dichloromethane and chloroform solutions. The mechanism of interaction MMI and Carb with TCNE have been studied by EPR spectroscopy. Spectral characteristics and formation constants are discussed in the terms of electron donor affinity of thioamides and the nature of the organic solvent used. The ionization potentials of donors were estimated from the CT transition energies of their complexes. The photolytic equilibrium constants of five thioamides are determined using pH-metric titrations.     

Spectral studies of heterocyclic β-diketonates of actinide,lanthanide, and transition metals

The results of absorption spectral studies of the 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone chelates of thorium, uranyl, neodymium, gadolinium, gallium, and iron are presented. These neutral chelates exhibit u.v. spectra very similar to that of the ligand, with slight bathochromic or hypsochromic shifts. The solution stability of the complexes in acetonitrile, ethanol, and chloroform was also studied and the lanthanide complexes were found to be the least stable. Sinha's parameter is calculated for the neodymium chelate to determine the relative degree of covalency upon complexation.     

β-Aminovinyl ketonates with heterocyclic fragments

-Aminovinyl ketones containing heterocyclic fragments (tetrahydro-1-6,2-benzothiazine 1,1-dioxide and 2,3-dimethyl-1-phenyl-2,5-dihydro-1H-pyrazole-5-one) (LH) and their complexes with 3d-metals (Co^II, Ni^II, Cu^II, and Zn^II) were synthesized. The obtained ligands give rise to two types of ML₂ chelates with coordinated (coordination number 6; Co, Ni, Zn) and uncoordinated carbonyl group in the pyrazole fragment (coordination number 5; Cu).Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 10, 2004, pp. 1709–1713.Original Russian Text Copyright © 2004 by Anpilova, Korshunov, Bicherov, Burlov, Borodkin, Zaletov, Uflyand, Garnovskii.This revised version was published online in April 2005 with a corrected cover date.     

Inclusion complexes of prochiral heterocyclic ketones with β-cyclodextrins and their reduction with sodium borohydride

Alkyl(2-furyl), alkyl(2-thienyl), and methyl pyridyl ketones form stoichiometric inclusion complexes with -cyclodextrins. Reduction of these complexes in aqueous solution of Na₂CO₃ at room temperature yields the corresponding secondary alcohols with an optical yield which attains 27%.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1621–1627, December, 1993.     

Microwave-induced and conventional heterocyclic synthesis: An antimicrobial entites of newer quinazolinyl-Δ2-pyrazolines

Heterocyclic compounds containing pyrazolines were reported to possess significant biological activity. Synthesis of 2-(ω-chloroacetonyl)-3-p-fluorophenyl-6-bromoquinazoline-4(3H)-ones (2), 2-(ω-hydrazinoacetonyl)-3-p-fluorophenyl-6-bromoquinazoline-4(3H)-ones (3) and 1′-[3H-3-p-fluorophenyl-4-oxo-6-bromoquinazoline-2-acetonyl]-3′-[1-o-chlorophenyl-3-methyl-5-azomethine-2-pyrazolidene]-5′-(substituted phenyl)-Δ²-pyrazolines (4a–j) have been described. Some of the new compounds were tested against bacteria (Gram –ve and Gram +ve) and fungi.     

Assessment of density functionals and force field methods on anion–π interaction in heterocyclic calix complexes

The performance of ten density functionals and four force field methods in describing non-covalent interactions have been assessed by studying the interaction energies and structures of the four anion–π complexes involving tetraoxacalix[2]arene[2]triazine and various anions. Their structures are optimized at MP2/6-311++G(d,p) level, and interaction energies are obtained at DF-MP2-F12/aug-cc-pVDZ level. The result shows that the functional M06-2X predicts the most reliable interaction energy, followed by wB97XD and BHandH. B97D slightly overestimates the interaction energy. Other functionals and force field methods seriously overestimate the interaction energy. For the structures, three functionals M06-2X, wB97XD and BH and H predict the most reliable results, followed by B97D. The force field methods predict the largest deviations. The present work suggests that the functional M06-2X is a reliable method to describe energies and structural properties of the large molecules involving the anion–π interactions.     

Synthesis and properties of heterocyclic β-nitronitrone: 1,2,2,5,5-pentamethyl-4-nitromethyl-3-imidazoline 3-oxide

The reaction of methyl nitrone, a derivative of 3-imidazoline 3-oxide, with methyl nitrate in the presence of PhLi results in -nitronitrone. The tnteraction of the latter with electrophiles involves, as a rule, the methylene group. Nitrile oxide, which is an 3-imidazoline 3-oxide derivative, has been generated by thermolysis ofgem-nitrooxime. This easily dimerizes to furoxan or undergoes regioselective 1,3-dipolar cycloaddition with alkenes.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 295–298, February, 1994.