Enzyme-Mediated Preparation of the Single Enantiomers of the Olfactory Active Components of the Woody Odorant Timberol®

Enantiomerically pure (3S)- 3a and - 3b , the olfactory active forms of 1-(2,2,6-trimethylcyclohexyl)hexan- 3-ol, components of the commercial woody odorant Timberol ^®, are obtained by lipase-PS-mediated enantioselective acetylation of the allylic alcohols 6 and 7 and of the saturated alcohol 3 . These materials, as mixtures of diastereoisomers, provided (3R)-configured transformation products. However, whereas in the conversion of 6 and 7 there is no diastereoselection, 3 provided the acetate of (1′S,3R,6′R)- 3c much more rapidly than that of the diastereoisomer (1′R,3R,6′S)- 3d (Scheme 3). Inversion of the configuration at C(3) of the side chain of the olfactory inactive (3R)-materials obtained as acetates in the enzymic treatment of 6 , 7 , and 3 also provided, eventually, the desired olfactory active (3S)-products.     

Determination of the Inductive Constant of the Succinimide Group from the Reaction Series of Thermolysis of Nitro Esters

The inductive constant σ* of the succinimide group was determined using the previously obtained equation correlating the rate constant k _l ofliquid-phase homolysis of the O-NO₂ bond in nitro esters with the σ* constants of electronegative substituents. The kinetics of thermolysis of N-nitroxymethyl- and N-(2-nitroxyethyl)succinimide in the melt and solutions was studied manometrically. Adequate data for k _l were obtained. The σ* constant of the succinimide group was determined to be 4.5. The σ* constants for the phthalimide group and some other imide substituents were determined by a similar procedure.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 6, 2005, pp. 954–957.Original Russian Text Copyright © 2005 by Goncharov, Dubikhin, Nazin, Fedorov, Shastin.     

Calculation of the Thermodynamic Properties of Silane and Disilane Derivatives and Modeling of the Thermolysis Process

Using the program package from the IVTANTERMO databank, the thermodynamic properties of CH₃SiH₃, CCl₃SiH₃, SiCl₃CH3, SiCl₃SiH₃, SiCl₃CCl₃, and SiCl₃SiCl₃ were calculated and the thermolysis process was studied for CCl₃SiH₃, SiCl₃CCl₃, and SiCl₃SiCl₃.     

Effect of the acyl group and the dodecylsulfonate chain on the inclusion of pyrene inside the cavity of β-cyclodextrin

The solubilization of pyrene in aqueous solution of β-cyclodextrin (β-CD) or its derivatives such as β-CD-hexanoyl, β-CD-benzoyl and β-CD-dodecylsulfonate was investigated by spectrophotometry. Linear and non-linear regression methods were used to estimate the association constants (K₁). A 1:1 stoichiometric ratio and different effects of the hexanoyl, benzoyl and dodecylsulfonate groups on the association constant were observed for the binary inclusion complex between pyrene and β-CD. The formation constant was shown to decrease when β-CD was modified by a dodecylsulfonate chain. The value of K₁ was 190 ± 10 L mol⁻¹ for the [pyrene/β-CD] complex and 145 L mol⁻¹ for the [pyrene/β-CD-dodecylsulfonate] complex. Partitioning of the pyrene molecules between the dodecylsulfonate chains and cyclodextrin cavities can explain the decrease in the association constant value. In the cases of β-CD-hexanoyl and β-CD-benzoyl derivatives, no association constants were detected. Results suggest that the high hydrophobicity of the hexanoyl and benzoyl groups prevents the inclusion of pyrene molecules inside the cyclodextrin cavity.     

The effect of the relative location of the double bond and the alkoxy group on the mass-spectrometric behavior of alkoxydihydropyranes

Conclusions The mass spectra ofthree 6-alkoxy-³-dihydropyranes and of three 6-alkoxy-²-dihydropyranes have been studied. As distinct from the previously studied 2-alkoxy-³-dihydropyranes, the dominant fragmentation pattern for the compounds under investigation is by retrodiene degradation. Furthermore, in the case of the ²-isomers the charge is preferentially localized on the olefin fragment while for the ³-isomers, it is located on the diene fragment.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1442–1444, June, 1970.     

Effect of the nature of the anion on the composition and structure of cobalt complex with monoethanolamine

A number of products formed in reactions of cobalt(II) salts with monoethanolamine (HEtm) in a neutral medium were synthesized and studied. X-Ray diffraction study showed that the nitrate and acetate form the dimers [Co(HEtm)₃][Co(Etm)₃](NO₃)₃ and [Co(HEtm)₃][Co(Etm)₃](CH₃COO)₃ · 8H₂O, respectively. In chloride solutions, cobalt is partially oxidized to give the trinuclear complex [Co^II{Co^III(Etm)₃}₂]Cl₃ · H₂Etm · 2H₂O. The reaction of the chelate [Co(Etm)₃] · 3H₂O with nitric acid is accompanied by complete protonation of the coordinated aminoethanolate ions, and the reaction with formic acid involves complete replacement of the coordinated ligand by acid residue anions and water molecules to give the coordination polymer {Co₂(μ-HCOO)₄(H₂O)₄} _n .     

Effect of the carbon atom coordination on the thermoactivated motion of the carbon-bonded trichloromethyl group

The reorientational motion of the trichloromethyl group depending on the environment of the carbon atom is considered based on the chlorine-35 nuclear quadrupole resonance (NQR) data. The study is performed for CCl₃ groups bonded to tri- and tetracoordinated carbon atoms in the crystalline compounds CCl₃CCl=NR (R = CH₂C₆H₅ and CCl₃CCl₃) and CCl₃CXClN=CClC₆H₄NO_2-n (X = H and Cl).₃₅Cl NQR studies of thermoactivated motion in 70 solid trichloromethyl-containing compounds are summarized. The ranges of activation energies of CCl₃ reorientations at tri- and tetracoordinated carbon atoms were determined to be 10-50 and 30-90 kJ/mole, respectively, the activation energy being markedly greater in the latter case. CCl₃ reorientations may be completely frozen by the bulky substituents which may be present along with CCl₃ in the tetracoordinated carbon bonds. Translated fromZhurnal Strukturnoi Khimii, Vol. 41, No. 4, pp. 737-746, July-August, 2000     

Enhancement of Stress Tolerance in the Polyhydroxyalkanoate Producers without Mobilization of the Accumulated Granules

Poly(3-hydroxybutyrate) [P(3HB)], a polymer belonging to the polyhydroxyalkanoate (PHA) family, is accumulated by numerous bacteria as carbon and energy storage material. The mobilization of accumulated P(3HB) is associated with increased stress and starvation tolerance. However, the potential function of accumulated copolymer such as poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)] remained unknown. In this study, Delftia acidovorans DS 17 was used to evaluate the contributions of P(3HB) and P(3HB-co-3HV) granules during simulated exogenous carbon deprivation on cell survival by transferring cells with PHAs to carbon-free mineral salt medium supplemented with 1 % (w/v) nitrogen source. By mobilizing the intracellular P(3HB) and P(3HB-co-3HV) at 11 and 40 mol% 3HV compositions, the cells survived starvation. Surprisingly, D. acidovorans containing P(3HB-co-94 mol% 3HV) also survived although the mobilization was not as effective. Similarly, recombinant Escherichia coli pGEM-T::phbCAB _Cn (harboring the PHA biosynthesis genes of Cupriavidus necator) containing P(3HB) granules had a higher viable cell counts compared to those without P(3HB) granules but without any P(3HB) mobilization when exposed to oxidative stress by photoactivated titanium dioxide. This study provided strong evidence that enhancement of stress tolerance in PHA producers can be achieved without mobilization of the previously accumulated granules. Instead, PHA biosynthesis may improve bacterial survival via multiple mechanisms.     

Sesquiterpenoids of the Sponge Dysidea fragilis of the North-Brittany Sea

The title sponge is shown to contain eight new sesquiterpenoids for which a common, unusual biogenetic origin is postulated. The compounds are shown to be: (–)-(1R*,4R*)-3-(3′-furyl)methyl-2-p-menthen-7-yl acetate ((–)- 8b ); two diols separated as the monoacetates (–)-(1S*,4R*)-3-(3′-furyl)methyl-l-hydroxy-2-p-menthen-7-yl acetate ((–)- 13a ) and the (–)-(1R*,4R*)-epimer (–)- 13b , the two C(4)-epimeric 4-ethoxy-3-(1′(7′),2′-p-menthadien-3′-yl)methyl-2-buten-4-olides ((+)- 14a and (–)- 14b ), (–)-3-(3′-furyl)methyl-7-nor-2-p-menthen-l-one ((–)- 11 ), (–)-(3Z)-1-(3′-furyl)-4,8-dimethylnona-3, 7-dien-2-yl acetate ((–)- 17 ), and (+)-3-(5′,7′-seco-2′(10′)-pinen-7′-yl)methylfuran ((+)- 15 ).     

Effect of the pH of the medium on the chemical shifts in the PMR spectra and on the distribution of the π-electron density

The dependence of the chemical shift of the ring protons on the pH of the medium for a number of 3-hydroxyquinoline derivatives was studied by PMR spectroscopy. The regions of ionization of the molecules, which correspond to the ranges of acidic, neutral, and alkaline media, were found. In D₂O, 3-hydroxyquinoline is present only in the uncharged hydroxy form. The presence of intramolecular hydrogen bonding in 4-dimethylaminomethyl-3-hydroxyquinoline has a substantial effect on the character of the dependence of the chemical shift on the pH of the medium; the existence of separate protonation of the nitrogen atoms of the ring and the side chain of 4-dimethylaminomethyl-3-hydroxyquinoline was established. The distribution of the -electron density in the 3-hydroxyquinoline molecule is in good agreement with its chemical behavior during electrophilic substitution.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1540–1545, November, 1971.     

Effect of the nature of the salt precursor of an oxide-hydroxide sorbent on the sorption of oxalate ions

Generalizations are made on the effect of the nature of a precursor (the original salt of a metal) on the sorption activity of hydrogels of oxidehydroxides (OHes) towards oxalate ions using the example of an OH obtained by the alkaline hydrolysis of chloride, perchlorate, and sulfate of Fe(III); chloride, sulfate, and nitrate of Al; and nitrate of Zr(IV). It is established that the sorption of C₂O ₄ ^2? on the studied OHes is described by the Langmuir equation. We find that the sorption activity depends on the nature of the precursor: Al₂(SO₄)₃ > Al(NO₃)₃ > AlCl₃ > ZrO(NO₃)₂ > Fe₂(SO₄)₃ > FeCl₃ > Fe(ClO₄)₃.     

A DFT Study of the Models of the Bronsted Acid Sites of Zeolite Catalysts

A systematic study of the different cluster models of the Bronsted site has been carried out in order to predict how the local structure influences the geometric parameters of the SiO(H)Al site and the harmonic frequencies of the characteristics vibrational modes of the bridging surface hydroxyl group. The performance of the B3LYP variant of the density functional theory (DFT) method is examined and compared with both SCF HF and MP2 approximations. In order to find the best molecular model for the Bronsted site, two series of derivatives based on the prototype model cores SiO(H)Al and HAlO₄ were considered. In the HAlO₄ series, H₃SiO(H)Al(OH)₂OSiH₃ and H₃SiO(H)Al(OSiH₃)₃ were investigated. Among the models in the SiO(H)Al series were H₃SiO(H)AlH₃, H₃SiO(H)Al(OH)₃, H₂(OH)SiO(H)Al(OH)₃, (OH)₃SiO(H)Al(OH)₃, and (H₃SiO)₃SiO(H)Al(OSiH₃)₃. The research reveals that the acidic OH bond length and its stretching frequency are greatly influenced by the H bond formed between the acidic proton and its next-nearest neighbor oxygen on the aluminum atom. The geometry and the frequencies for the larger models predicted at the B3LYP/D95(d,p) level are in good agreement with the experiments, suggesting that the B3LYP/D95(d,p) theory is reliable for a study of the Bronsted site. This study also suggests that the OH terminated models are not suitable as models for the SiO(H)Al site due to the strong dipole moment of the OH group, which strongly affects the acidic H.     

Investigation of the homogeneity of the distribution of doped elements in oxide single crystals

Summary The homogeneity of the distributions of doped V and Ti in Al₂O₃:V³⁺, Y₃Al₅O₁₂:V³⁺, Al₂O₃:Ti³⁺, Y₃Al₅O₁₂:Ti³⁺ single crystals was studied by means of laser emission microanalysis. The applied statistical methods include one-way variance analysis, two-way variance analysis, regression models and the gradient method.     

Effect of the carbon atom coordination on the thermoactivated motion of the carbon-bonded trichloromethyl group

The reorientational motion of the trichloromethyl group depending on the environment of the carbon atom is considered based on the chlorine-35 nuclear quadrupole resonance (NQR) data. The study is performed for CCl₃ groups bonded to tri- and tetracoordinated carbon atoms in the crystalline compounds CCl₃CCl=NR (R = CH₂C₆H₅ and CCl₃CCl₃) and CCl₃CXClN=CClC₆H₄NO_2-n (X = H and Cl).₃₅Cl NQR studies of thermoactivated motion in 70 solid trichloromethyl-containing compounds are summarized. The ranges of activation energies of CCl₃ reorientations at tri- and tetracoordinated carbon atoms were determined to be 10-50 and 30-90 kJ/mole, respectively, the activation energy being markedly greater in the latter case. CCl₃ reorientations may be completely frozen by the bulky substituents which may be present along with CCl₃ in the tetracoordinated carbon bonds. Translated fromZhurnal Strukturnoi Khimii, Vol. 41, No. 4, pp. 737-746, July-August, 2000     

Synthesis of fragments of the glycocalyx glycan of the parasite Schistosoma mansoni

The chemical synthesis of alpha-L-Fucp-(1 --> 3)-beta-D-GalpNAc-(1 --> 4)-beta-D-GlcpNAc-(1 --> 3)-alpha-D-GalpO(CH2)5NH2, beta-D-GalpNAc-(1 --> 4)-[alpha-L-Fucp-(1 --> 3)-]beta-D-GlcpNAc-(1 --> 3)-alpha-D-GalpO(CH2)5NH2, and alpha-L-Fucp-(1 --> 3)-beta-D-GalpNAc-(1 --> 4)-[alpha-L-Fucp-(1 --> 3)-]beta-D-GlcpNAc-(1 --> 3)-alpha-D-GalpO(CH2)5NH2 is described. These structures represent fucosylated oligosaccharide fragments of the glycocalyx glycan of the cercarial stage of the parasite Schistosoma mansoni, and in protein-conjugated form they are potential diagnostics in the search for antibodies raised against the glycan in the serum of infected humans.     

19F NMR investigation of the polarities of the metal-oxygen bonds and the electronegativities of the Ph n M groups in organometallic derivatives of tris(4-fluorophenyi)stannanol

A number of Ar₃MOM*Ph₃ compounds containing Group lVB metals were synthesized or generated in solution. On the basis of¹⁹F NMR data for (4-FC₆H₄)₃SnOMPh₃ compounds, the relative polarities of the M-O bonds and relative electronegativities of the Ph₃M groups were evaluated and the latter values were found to correlate with the electronegativities of the central metal atoms. The variation of the shielding of the heavy nuclei in Ph₃SnOMPh₃ and Ph₃PbOMPh₃ does not reflect the variation in the electron density on the tin and lead atoms.     

Assessing the Viability of the Methylsulfinyl Radical-Ozone Reaction

Although integral to remote marine atmospheric sulfur chemistry, the reaction between methylsulfinyl radical (CH₃SO) and ozone poses challenges to theoretical treatments. The lone theoretical study on this reaction reported an unphysically large barrier of 66 kcal mol⁻¹ for abstraction of an oxygen atom from O₃ by CH₃SO. Herein, we demonstrate that this result stems from improper use of MP2 with a single-reference, unrestricted Hartree-Fock (UHF) wavefunction. We characterized the potential energy surface using density functional theory (DFT), as well as multireference methodologies employing a complete active-space self-consistent field (CASSCF) reference. Our DFT PES shows, in contrast to previous work, that the reaction proceeds by forming an addition adduct [CH₃S(O₃)O] in a deep potential well of 37 kcal mol⁻¹. An O−O bond of this adduct dissociates via a flat, low barrier of 1 kcal mol⁻¹ to give CH₃SO₂+O₂. The multireference computations show that the initial addition of CH₃SO+O₃ is barrierless. These results provide a more physically intuitive and accurate picture of this reaction than the previous theoretical study. In addition, our results imply that the CH₃SO₂ formed in this reaction can readily decompose to give SO₂ as a major product, in alignment with the literature on CH₃SO reactions.     

Synthesis of Re-Ru heterobimetallic polyhydride complexes. Study of the influence of ligands bonded to the monometallic precursors on the nature of the isolated binuclear complexes

The reaction of K[H₆ReL₂] with [RuHCl(CO)(PPh₃)_3−x {P(OPrⁱ}₃)_x](L₂ = (PMePh₂)₂, dppe, (AsPh₃)₂, or (PPh₃)₂; x = 0, 1 or 2) leads to [L₂(CO)HRe(μ-H)₃RuH(PPh₃)_2−y{P(OPrⁱ)₃}_y] (x = 0 or 1, Y = 0; X = 2, Y = 1(L₂ = PPh₃)) in a first step. Under the reaction conditions most of these complexes react rapidly with the liberated phosphine giving [L₂(CO)Re(μ-H)₃Ru(PPh₃)_3−y- {P(OPrⁱ)₃}_y] (L₂ = (PMePh₂)₂ or dppe, Y = 0; L₂ = (PPh₃)₂, Y = 1) as the only iso complexes. The structure of [(PMePh₂)₂(CO)Re(μ-H)₃Ru(PPh₃)₃] has been establishedby X-ray structure analysis. The complex [(PPh₃)₂(CO)Re(μ-H)₃Ru(PPh₃)₂(P(OPrⁱ)₃)] reacts with molecular hydrogen under pressure to generate [L₂(CO)HRe(μ-H)₃RuH(PPh₃)(P(OPrⁱ)₃) as the sole product.     

Kinetics of the decomposition of calcium carbonate in the presence of Bi2O3

Former studies concerning the formation of the compounds in the pseudobinary systems of Bi₂O₃-MO type (M =Ca, Sr, Ca+Sr) have shown that the reaction which occurs with the highest rate is that between Bi₂O₃ and CaO. In the present work CaCO₃ was used as CaO source. We carried out an investigation of the thermal decomposition of CaCO₃ in the presence of Bi₂O₃ in comparison with the decomposition of pure CaCO₃.The presence of Bi₂O₃ exerts a complex influence on the CaCO₃ decomposition acting on the nucleation as well as on the diffusion of CO₂. The decomposition of the samples with low Bi₂O₃ content follows the mechanism of a contracting sphere. A change from surface nucleation to bulk nucleation is recorded for higher amounts of Bi₂O₃.     

Improvement of the reactivity and selectivity of the oxo-Diels-Alder reaction by steric modification of the salen-chromium catalyst

Salen-chromium(III) complexes bearing sterically demanding substituents at the 3 and 3′ positions are applied for the oxo-Diels-Alder reaction of various aldehydes with Danishefsky’s diene. The readily-accessible complex bearing a bulky 3-phenylpent-3-yl substituent revealed its potential affording the cycloadducts with improved reactivity and excellent selectivities up to 96% ee, being considerably superior to the classic Jacobsen’s catalyst.