Aromatic derivatives of 2H-pyrimidino[5,6-b]-1,4-thiazine

5-R¹3-(4-R-Phenyl)-2H-pyrimidino[5,6-b]-1,4-thiazines [R¹=N(CH₃)₂ or OCH₃], which exist primarily in the 2H form, were synthesized by the reaction of -bromoacetophenones with 4-R¹-5-amino-6-thiopyrimidines.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 275–277, February, 1987     

Organometallic complexes containing thiosemicarbazone and related ligands. Part II(1). η3-allyl dicarbonyl complexes of molybdenum(II) with attached thiosemicarbazone ligands

Summary The -allylmolybdenum(II) complexes [MoX(CO)₂-(NCMe)₂(³-C₃H₄R)] (X=Cl, Br and I; R=H and 2-Me) react either in dichloromethane or acetonitrile with thiosemicarbazones to give the new complexes [MoX-(CO)₂(RRCNNHCSNH₂)(³-C₃H₄R)] (R=H or Me; R'=Me, Et, Pr or Ph)via displacement of acetonitrile ligands.     

Eu(III) extraction by bis(2-ethylhexyl)phosphoric acid and 8-hydroxyquinoline in dodecane from perchlorate medium

Europium(III) was extracted by bis(2-ethylhexyl)phosphoric acid (HDEHP) and 8-hydroxyquinoline (HQ) in dodecane from aqueous perchlorate media of constant ionic strength (0.1M; H⁺, NaClO₄). Slope analysis of the data indicate that three molecules of HDEHP or HQ are attached to Eu³⁺. Extraction constants were obtained at different temperatures. The data were used to calculate the thermodynamic parameters (G, H and S) for the extraction process in the two systems. When using mixtures of crown ethers with HDEHP no synergism was observed.     

Quantum-chemical investigation of the protonated forms of 2-(2-furyl)pyrrole

The electron and conformational structures, as well as the internal rotation, of 2-(2-furyl)pyrrole and its -protonated forms were studied by the MNDO method with complete optimization of the geometry. In conformity with the experiments (PMR), the two delocalized cations with a cis orientation of the heteroatoms that are formed as a result of protonation of the pyrrole or furan ring have the greatest and virtually equal stabilities (H=738.7 and 740.6 kJ/mole).Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 746–753, June, 1991.     

Use of Suzuki cross-coupling as a route to 2-phenoxy-6-iminopyridines and chiral 2-phenoxy-6-(methanamino)pyridines

The anisyl boronic acids, 2-OMe-3-R²-5-R¹-C₆H₂B(OH)₂ (R¹=R²=H (a); R¹=H, R²=Ph (b); R¹=Me, R²=H (c); R¹=Cl, R²=H (d); R¹=t-Bu, R²=H (e)), have been employed in Suzuki cross-coupling reactions with either 2-bromo-6-formylpyridine (I) or 2-bromo-6-acetylpyridine (II) generating, following a facile deprotection step, the 2-phenoxy-6-carbonylpyridines, 2-(2′-OH-3′-R²-5′-R¹-C₆H₂)-6-(CHO)C₅H₃N (R¹=R²=H (1a); R¹=Me, R²=H (1c); R¹=Cl, R²=H (1d); R¹=t-Bu, R²=H (1e)) and 2-(2′-OH-3′-R²-5′-R¹-C₆H₂)-6-(CMeO)C₅H₃N (R¹=R²=H (2a); R¹=H, R²=Ph (2b)). Condensation reactions of 1 and 2 with 2,6-diisopropylaniline proceed smoothly to give the 2-phenoxy-6-iminopyridines, 2-(2′-OH-3′-R²-5′-R¹-C₆H₂)-6-{CHN(2,6-i-Pr₂C₆H₃)}C₅H₃N (R¹=R²=H (3a); R¹=Me, R²=H (3c); R¹=Cl, R²=H (3d); R¹=t-Bu, R²=H (3e)) and 2-(2′-OH-3′-R²-5′-R²-C₆H₂)-6-{CMeN(2,6-i-Pr₂C₆H₃)}C₅H₃N (R¹=H, R²=Ph (4a), R¹=H, R²=Ph (4b)). Reduction of the imino unit (and concomitant C-C bond formation) in 3 can be achieved by treatment with trimethylaluminium or methyllithium which, following hydrolysis, furnishes the racemic chiral 2-phenoxy-6-(methanamino)pyridines, 2-(2′-OH-3′-R²-5′-R¹-C₆H₂)-6-{CHMe-NH(2,6-i-Pr₂C₆H₃)}C₅H₃N (R¹=R²=H (5a); R¹=Me, R²=H (5c); R¹=Cl, R²=H (5d); R¹=t-Bu, R²=H (5e)). This work represents a straightforward and rapid synthetic route to libraries of sterically and electronically variable phenoxy-substituted imino- and methanamino-pyridines, which are expected to act as useful ligands or proligands for late and early transition metal-mediated alkene polymerisation catalysis.     

The solid-state structure of (+)-(i)-menthyl 2-formamido-4, 4,4-trifluorobutanoate and the hydrogenation of the 2-butenoate precursor

Hydrogenation ofZ-(–)-(1R, 3R, 4S)-menthyl 2-formamido-4,4,4-trifluoro-2-butenoate catalyzed by Pd/C was performed at atmospheric pressure to yield a mixture of (2R, 1R, 3R, 4S)- and (2S, 1R, 3R, 4S)-menthyl 2-formamido-4,4,4-trifluorobutanoate diastereomers in a 5545 ratio, respectively. Repeated fractional crystallization from ethyl acetate and vapor diffusion of petroleum ether afforded (+)–(2S, 1R, 3R, 4S)-menthyl 2-formamido-4,4,4-trifluorobutanoate as clear colorless, crystalline prisms which were subjected to single-crystal X-ray diffraction analysis. The crystals belong to the orthorhombic system P2₁2₁2₁, and at 213 K:a=5.054(1),b= 10.000(2),c=32.707(1) Å,V=1652.9(4) ų,Z=4,R(F)=0.040, andR _w (F)=0.037. The finding of the (2S)-configuration for the formamido-acid portion of the (+)-ester enabled the configurational assignment of the asymmetric hydrogenation products ofZ-methyl 2-formamido-4, 4,4-trifluoro-2-butenoate catalyzed by chiral diphosphine/rhodium(I) complexes.     

Zur Reaktion von Fluorsilanen mit lithiierten Aminen

The reaction of fluorosilanes with lithium salts of bulky amines like tetramethyl-piperidine and di-tert. butylamine leads to stable aminofluorosilanes of the type R-SiF₂-NRR [R=F, C(CH₃)₃, C₆H₅, C₆H₄N(CH₃)₂]. Lithium salts of silylamines react analogously: R₂Si(NR-SiF₂R)₂ (R=R= =CH₃, R=C₆H₅). An eight membered Si–N-ring is obtained in the reaction of a disubstituted silylaminofluorosilane with the dilithium salt of a silylamine. The mass-,¹H-, and¹⁹F-NMR spectra of the above mentioned compounds are reported.     

Demetallation of coordination compounds of nickel with tetradentate ligands based on S-substituted isothiosemicarbazides

The passage of dry gaseous hydrogen chloride through chloroform solutions or acetone suspensions of S-substituted N¹,N⁴-di(salicylidene)isothiosemicarbazidates of nickel (Ni(LRR)) has led to a demetallization reaction with the liberation in the free state of S-substituted N¹,N⁴-di(salicylidene)isothiosemicarbazides with the general formula N₂LRR (where R is H and R is CH₃ (I); R is H and R is C₂H₅ (II); R is H and R is C₃H₇ (III); R is H and R is C₇H₇ (IV); and R is CH₃ and R is CH₃ (V)). The IR spectra of (I-IV) each showed bands characteristic for an aromatic ring and groups in the 1600–1500 cm^–1 region, with a band of the deformation vibrations of an OH group at 1300 cm^–1. The PMR spectra in CDCl₃ each had two singlets at 12.15-11.25 and 9.00-8.36 ppm which were assigned, respectively, to the protons of an OH group and those of a =CH group. A multiplet in the 7.70-6.83 ppm region belonged to the protons of benzene rings. In the region of lower fields there were the signals of the substituents R and R. In the mass spectra of (I-V), the peaks of the molecular ions, and also the characteristic fragments OH, R, SR, and HSR have been detected.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 21, No. 5, pp. 604–608, September–October, 1985.     

Stereochemical specificity of the palladium-catalyzed hydrogenation of cyclohexa[b]thiopyrans and their derivatives

Conformationally and configurationally homogeneous 2-R¹-4-R²-cis-1-thiadecalins with an equatorial orientation of the substituents attached to the C(₂) and C(₄) atoms were isolated as the final reduction products in the catalytic hydrogenation on palladium of 2-R¹-4-R²-4H(6H)-cyclohexa[b]thiopyrans, cis-3-R¹-5-R²-2-thiabicyclo[4.4.0]-^1,6-decenes, and 2-R¹-4-R²-cyclohexa[b]thiopyrylium tetrafluoroborates and trifluoroacetates. cis-3-R¹-5-R²-2-Thiabicyclo[4.4.0]-^1,6-decenes were obtained as intermediates in the incomplete reduction of 2-phenyl- and 2,4-diphenyl-4H-cyclohexa[b]thiopyrans and 2-(4-methoxyphenyl)-4-R²-cyclohexa[b]thiopyrylium salts; 2-R¹-4-R²-6H-cyclohexa[b]thiopyrans undergo complete reduction of the double bonds of the heteroring. The hydrogenation products were oxidized to sulfoxides and sulfones.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 614–619, May, 1987.     

The supramolecular structures and reactivities of some complexes of chiral crown ethers with borane ammonia

Whereas 1 1 crystalline complexes have been isolated between borane ammonia and methyl 4,6-O-benzylidene-2,3-dideoxy--d-galactopyranosido [2,3-b]-1,4,7,10,13,16-hexaoxacyclo-octadecane (1), methyl 4,6-O-benzylidene-2,3-dideoxy--d-mannopyranosido [2,3-b] (methyl 4,6-O-benzylidene-2,3-dideoxy--d-mannopyranosido [2,3-k]-1,4,7,10,13,16-hexaoxacyclo-octadecane (3), and (1R,2R,7R,24R)-3,5,8,11,14,17,20,23,26,28-decaoxatricyclo-[21.4.0.0^2,7]octacosane (4), the hosts, methyl, 4,6-O-benzylidene-2,3-dideoxy--d-mannopyranosido[2,3-b] 1,4,7,10,13,16-hexaoxacyclo-octadecane (2) and 1,4 1,4 3,6 3,6-tetra-anhydro-2,2 5,5-bis-O-oxydiethylenedi-d-mannitol (5) have yielded 2 1 (guest:host) crystalline complexes with borane ammonia as guest. X-ray analyses of the supramolecular structures of BH₃NH₃ ·1, (BH₃NH₃)₂ ·2, BH₃NH₃ ·3, BH₃NH₃ ·4, and (BH₃NH₃)₂ ·5 have been carried out and BH₃NH₃ ·1, BH₃NH₃ ·2, and (BH₃NH₃)₂ ·5 have been shown to reduce acetophenone with enantiomeric excesses of 5, 13, and 10% respectively. Supplementary Data relating to this article (atomic coordinates of the hydrogen atoms and thermal parameters) are deposited with the British Library as Supplementary Publication No. SUP 82017 (74 pages).Dedicated to Professor H. M. Powell.     

Photoluminescence Spectra and Crystallization of θ-Al2O3 and α-Al2O3 from AlOOH-Fe(NO3)3 Gels

Diphasic boehmite derived unseeded and seeded (by either -Al₂O₃, -Fe₂O₃, or Fe(NO₃)₃) alumina gel planar monoliths were examined by DTA, XRD and photoluminescence spectroscopy. Luminescence spectra enable sensitive monitoring of the - and -Al₂O₃ crystallization in heat-treated gels due to Cr³⁺ impurity traces. Fe(NO₃)₃ unlike other seeds effectively influences crystallization of both - and -Al₂O₃. The present results are interpreted as prevailing solution or Fe³⁺ ion effect on the crystallization process.     

ESR spectroscopic investigation of steric and polar factors in the addition of radicals to unsaturated compounds

The rate constants of the addition of CCl₃CH₂ClCH₃(R⁶) radicals to -methyl-styrene, styrene, methyl methacrylate, methyl acrylate, and acrylonitrile and of CCl₃CH₂(CH₃)₂(R⁷) radicals to styrene, methyl acrylate, and acrylonitrile were determined by ESR spectroscopy. It was shown that the radicals R⁶ and R⁷ possess approximately equal reactivity in addition to unsaturated compounds, despite the difference in the donor-acceptor properties of the substituents at the vinyl group. In a comparison of the reactivity of radicals R⁶ and R⁷ with the reactivity of radicals CCl₃CH₂H₂(R¹), CCl₃CH₂HCH₃(R³), CCl₃CH₂HCl(R⁴), and ClCH₂CH₂Cl₂(R⁵) [1] in addition reactions, it was shown that polar and steric effects of the substituents situated in the -position to the radical site of the above-mentioned radicals, as well as the donor-acceptor properties of the substituents at the vinyl group in the unsaturated compounds, lead to appreciable changes in reactivity.A. N. Nesmeyanov Institute of Heteroorganic Compounds, Russian Academy of Sciences, 117813 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 136–141, January, 1992.     

The thermal decomposition of cerium(III) nitrate

The thermal decomposition of anhydrous Ce(NO₃)₃ has been studied. The thermal decomposition reaction is described by the second order kinetic equation, [1/(1–)]–1=kt. The apparent activation energy was determined asE _a=104 kJ mol^–1 while the enthalpy of the reaction was estimated asH _r=111.1 kJ mol^–1. The decomposition reaction differs from that observed for Nd(NO₃)₃.

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Zusammenfassung Die thermische Zersetzung von wasserfreiem Ce(NO₃)₃ wurde untersucht. Die thermische Zersetzung wird durch die Geschwindigkeitsgleichung zweiter Ordnung[1/(1–)]–1=kt, beschrieben. Für die scheinbare Aktivierungsenergie wurde ein Wert von 104 kJ mol^–1 und für die Enthalpie der Reaktion ein Wert von 111,1 kJ mol^–1 ermittelt. Die Zersetzungsreaktion unterscheidet sich von der für Nd(NO₃)₃.

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. : [1/(1–)]– 1=kt. a, 104 · ^–1, H _r, 111.1 · ^–1. .

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The authors wish to thank the Council for Scientific and Industrial Research and the University of Pretoria for financial assistance.     

Empirical equations of state for adsorption layer: Alkylthiopolyoxyethylene glycols

Surface tension isotherms ofn-alkylthiopolyoxyerhylene glycols:n-C _x H_2x+1S(CH₂CH₂O) _y H, wherex=5 to 8,y=3 or 4, were approximated with orthogonal polynomials to get good quality values of surface pressure (II) and molar area of the adsorbed layer (). The modified Volmer (*(–₀)=Z*R*T) van der Waals and virial equations of state were used to correlate and in terms of real two-dimensional gas. The combination of Volmer and van der Waals equations of state made it possible to determine the interaction energy, , which was prescribed to cohesion of hydrophobic chains in the adsorption layer. The value of for the amphiphiles in question was in the range 0.97–1.91R*T and the average contribution per methylene group was ca. 0.21R*T.The Lennard-Jones potentials calculated from second virial coefficient were of the same range as , but no clear relation was found between their values and number of structure elements of the alkylthiopolyoxyethlene glycols.Presented during 7th International Conference: Surface and Colloid Science, July 7–13, 1991, Compiegne, France     

Synthesis and properties of 5-furyl(aryl)-Δ2-1,2,4-triazolines and -Δ2-1,3,4-thiadiazolines. Molecular and crystal structure of 2-acetylamino-5-phenyl-Δ2-1,3,4-thiadiazoline

We show that upon acylation of arylidene amidrazones of 5-nitro-2-furancarboxylic acid, 3-(5-nitro-2-furyl)-²-1,2,4-triazolines or 5-(5-nitro-2-furyl)-1,2,4-triazole are formed (depending on the structure of the arylidene moiety). ²-1,3,4-thiadiazolines are obtained by reaction of thiosemicarbazones of aromatic and furaldehydes and furan ketones. We discuss schemes for closure of the triazolidine, triazole, and thiadiazoline rings. We describe the molecular structure of 2-acetylamino-4-acetyl-5-phenyl-²-1,3,4-thiadiazoline.Kuban State Technological University, Krasnodar 350072. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1337–1344, October, 1994. Original article submitted October 11, 1994.     

Intensity of the η(C≡C) Bands in the IR Spectra of Acetylene Derivatives and σR 0 Constants of Organosilicon,Organogermanium, and Organotin Substituents

The integral absorptivities of shape-characteristic (CC) bands in the IR spectra of 66 acetylene derivatives RCCX (R = H, Me₃M; X are inorganic and organic substituents) are related by a common linear equation to the _R ⁰ constants of the R and X substituents. The _R R⁰ constants of 10 Alk₃M substituents were calculated. The _R ⁰, _R , and _R ⁺ constants of Me₃M substituents were analyzed. The positive _R ⁰ values (0.12, 0.06, and 0.04 for R = Si, Ge, and Sn, respectively) suggest that in the ground electronic state of Me₃MCCX molecules the resonance acceptor effect of the Me₃M substituents (d, conjugation) prevails over donor (, conjugation). The first effect attenuates and the second enhances as the atomic number of M increases.     

On the possibility of existence of η5-π-complexes of C60 fullerene: π-complexes with silicon

Qualitative estimates of possibility of the formation of fullerene ⁵--complexes have been carried out by the MNDO/PM3 method. It was shown, as exemplified by the C₆₀ cluster, that the introduction of five univalent functional groups R (R = H, Cl, Br) to -positions of a separate pentagon of C₆₀ with the formation of [R₅C₆₀]^– anions results in a pronounced increase in the -electron density on the atoms of this five-membered cycle and more favorable conditions for the formation of -bonds with the ⁵-ligand. The nature of the interaction between the atoms of the separate cycle in [R₅C₆₀]^– anion and ⁵-ligand was analyzed by the example of hypothetical sandwich systems R₅C₆₀SiCp. Half-sandwich complexes R₅C₆₀SiX (X = H, Cl) were also investigated. The local energy minima were found on the potential energy surfaces (PES) of systems R₅C₆₀SiCp and R₅C₆₀SiX with C_5p symmetry. These systems transform barrirlessly into q5-7E-complexes with the angular structure if the symmetry restrictions are removed. The most favorable conditions for ⁵--complexes of R₅C₆₀ to form are realized for R = H. The results obtained were compared to those of semiempirical and nonempirical calculations of bis (cyclopentadienyl) silicon.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2422–2429, October, 1996.     

The quest for a stable silyne, RSi ≡ CR′. The effect of bulky substituents [1]

The two major fundamental obstacles which so far have prevented theisolation of stable silynes, RSiCR (1), are: (a)the existence of more stable isomers, e.g., RRC=Si: (2) and(b) their extremely facile (exothermic) dimerication. The steric andelectronic effects of various substituents R and R (R = alkoxy,alkyl, aryl and silyl; R = alkyl and aryl groups) on the stability ofRSiCR relative to the isomeric RRC=Si:(E(1-2)), and on the energy of dimerization tothe corresponding 1,3-disilacyclobutadienes (E(D)), werestudied computationally using density functional theory (DFT) and theONIOM method. The goal was to find a combination of substituents thatwill make RSiCR more stable than RRC=Si: and whichwill also prevent its dimerization. For R = R = H,E(1-2)) = 40.7 kcal/mol (i.e., 2 islower in energy than 1), and E(D) = –104.0kcal/mol. 1, R = OH, R = m-Tbt 2,6-bis[bis(silyl)methyl]phenyl, is by 11.1 kcal/mol morestable than the isomeric silylidene 2. However, thedimerization of 1, R = OH, R = m-Tbt remains highlyexothermic (by 101 kcal/mol). 1, R = R = m-Tbt and1, R = (t-Bu)₃Si, R = m-Tbt, are by 5.8 and 2.0kcal/mol, respectively, less stable than the corresponding 2.However, the dimerization of 1, R = (t-Bu)₃Si, = m-Tbt is exothermic by only 12 kcal/mol. For1, R = (t-Bu)₃Si, and R = Tbt 2,6-bis[bis(trimethylsilyl)methyl]phenyl, the corresponding1,3-disilacyclobutadiene dimer 3, dissociates spontaneously.Thus, (t-Bu₃Si)SiCTbt is predicted to be kineticallystable towards both, isomerization to (t-Bu₃Si)TbtC=Si: anddimerization to 3, making it a viable synthetic target. Thereported energies were calculated atB3LYP/6-31G^**//B3LYP/3-21G^*; good agreement is found betweenthe DFT and the ONIOM results.     

Phytoecdysteroids of plants of the genusSilene X. Sileneoside E — 2-Deoxy-α-ecdysone 3-O-β-D-glucopyranoside — FromSilene brahuica

A new ecdysteroid has been isolated from the epigeal organs ofSilene brahuica Boiss. — 2-deoxy--ecdysone 3-O--D-glucopyranoside (I), C₃₃H₅₄O₁₀, mp 195–196°C, [] _D ²⁰ + 44.4° (methanol). The enzymatic hydrolysis of (I) led to 2-deoxy--ecdysone. Details of the IR, UV, mass, and¹H and¹³C NMR spectra of all the compounds are given.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 323–326, May–June, 1986.     

Electron structure of the V2 molecule derived from DV-Xα data

Conclusions The electron structure of the V₂ molecule has been calculated by means of the DV-X method. The configuration 3_u ⁴6_g ²7_g ²(l_g)² has been obtained for the ground state, which corresponds to a quintuple bond, and the equilibrium state 1.78 Å. The term of the ground state³_g ^– and the bond length are in agreement with the experimental data.Translated from Izvestiya Akadeinii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 232–235, September, 1985.The authors wish to express their gratitude to A. N. Ivanov and V. K. Gryaznov for the provision of the program for the calculation of the atomic Hartree-Fock functions.