bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reactivities of Stable Rotamers. XXVI. Some Bimolecular Elimination Reactions of 9-(2-Substituted 1-naphthyl)fluorene Rotamers
Authors: Sonoda Yoriko , Tsukahara Jiro , Nakamura Nobuo , Oki Michinori 
Published: July 2006

Abstract
Various elimination reactions which are believed to proceed with E2-type mechanisms have been examined on 9-[2-(1,2-dibromoethyl)-1-naphthyl]fluorene and 9-[2-(1-hydroxy-2-trimethylsilylethyl)-1-naphthyl]fluorene rotamers. Generally, the reaction of the sp rotamers was faster than that of the ap by a factor of 2–9. The results are attributed to the steric effects that are operative in the ap form.
Catalytic Hydrogenation and Cracking of Anthracene over MoCl3–LiCl–KCl and NiCl2–LiCl–KCl Salts
Authors: Song Chunshan , Ono Tomohiro , Nomura Masakatsu 
Published: July 2006

Abstract
The MoCl3– and NiCl2–LiCl–KCl salts, which are effective coal liquefaction catalysts, promoted the hydrogenation of anthracene (at 400 °C for 1 h with 9.8 MPa H2) and afforded tetrahydro- and octahydro- as well as dihydroanthracene as major products. However, these catalysts did not remarkably enhance the ring-opening cracking reactions. A comparative examination suggested that the addition of LiCl–KCl to MoCl3 and NiCl2 suppressed their cracking ability and improved their hydrogenation selectivity.
The Addition Effect of CH3I on the Ignition of CH4
Authors: Takahashi Kazuo , Inomata Tadaaki , Moriwaki Takao , Okazaki Satiko 
Published: July 2006

Abstract
Measurements and calculations of ignition delay times were performed in a mixture of CH4–CH3I–O2–Ar in order to understand the characteristics of compouds including iodine during ignition. CH3I accelerated the ignition of CH4 more than CH3Cl did, but less than CH3Br did. The remarkably small bond-dissociation energies of CH3I and HI, in comparison to these of other halomethanes, were the major cause of the characteristic behavior.
Structure of a Cumulene Bearing Bulky Substituents. X-Ray Study of 1,1,4,4-Tetrakis(trimethylsilyl)butatriene
Authors: Morimoto Yoshihiro , Higuchi Yoshiki , Wakamatsu Kuni , Oshima Koichiro , Utimoto Kiitiro , Yasuoka Noritake 
Published: July 2006

Abstract
The structure of cumulene bearing bulky substituents, 1,1,4,4-tetrakis(trimethylsilyl)butatriene, has been determined by an X-ray diffraction method. The molecule is centrosymmetric, and the variation in carbon–carbon double bonds has been observed. The distance of the central C=C bond is 1.276(8) Å, whereas that of the terminal C=C bond is 1.319(6) Å. These bond lengths are very similar to the unsubstituted butatrienes and the influence of bulky trimethylsilyl groups is not recognized in this context. Some distortions have been observed in the bond angles concerning the trimethylsilyl groups; the overcrowded environment of the central C=C bond seems to make this less reactive.
Activation of Dinitrogen over Various Raney Type Metal Catalysts
Authors: Ogata Yoichi , Aika Ken-ichi , Onishi Takaharu 
Published: July 2006

Abstract
Raney Ni, Rh, Re, and Ir adsorbed molecular nitrogen which was stable up to about 300 K. Raney Fe, Co, Ni, Ru, Rh, Ir, and Pt adsorbed atomic nitrogen which was desorbed around 700 or 800 K. The XPS spectra of atomically adsorbed nitrogen was observed on Co, Ni, and Ru samples. While the per-weight activity of Raney Ru for isotopic equilibration of N2 is much higher than that of 5% Ru–K/AC, those of other Raney metals are lower than those of 5% metal–K/AC.
The High-Temperature Reaction of Iron with Sulfur Dioxide
Authors: Ota Ken-ichiro , Sugimoto Hiroyuki , Fueki Kazuo 
Published: July 2006

Abstract
The reaction of Fe with SO2 has been studied in the temperature range from 923 K to 1123 K and in the pressure range from 1.3 kPa to 101 kPa. The reaction obeyed the parabolic law except for the initial period, and the rate constant was equal to that in O2. In the scale, Fe3O4, FeO, and FeS were found as the reaction products. Among them, FeS was formed only in the initial period of the reaction and stayed at the scale/metal interface. The constant amount of sulfide in the scale became larger at higher temperatures or at lower SO2 pressures. The sulfide formation in the initial period of the reaction might cause the increase in the corrosion of Fe at low pressures of SO2 and cause the difference from the corrosion by O2.
Study of Conformers of 2,2′-, 3,3′-, and 4,4′-Dimethylbiphenyls in the Phosphorescent Triplet States by Electron Spin Resonance and Phosphorescence
Authors: Tanigaki Katsumi , Taguchi Noriyuki , Yagi Mikio , Higuchi Jiro 
Published: July 2006

Abstract
For the phosphorescent triplet (T1) states of symmetrically-substituted dimethylbiphenyls, the relationship between the twisting angle of the two aromatic rings and the zero-field splitting parameters is discussed in terms of the ESR spectra. Two sets of ESR spectra observed for 2,2′- and 3,3′-dimethylbiphenyls (2DMBP and 3DMBP) are precisely assigned to the corresponding s-cis or s-trans conformer. The results clarify the inadequate assignment of the spectra of these molecular species in the previous literature. The lifetime obtained for the s-cis conformer is different from that of the s-trans one for both 2DMBP and 3DMBP. Examining the T1–T1 energy transfer from one conformer to the other, the relative locations for the T1 states of s-cis and s-trans conformers are obtained, even if phosphorescence measurements do not provide each isolated spectrum: ET (s-cis-3DMBP)&lt;ET(s-trans-3DMBP) and ET(s-cis-2DMBP)&gt;ET(s-trans-2DMBF).
Syntheses of Acetyl-1-bromopyrenes
Authors: Minabe Masahiro , Mochizuki Hidehiro , Yoshida Masaaki , Toda Takashi 
Published: July 2006

Abstract
The reaction of 1-bromopyrene with acetic anhydride in the presence of aluminium chloride afforded an ipso-substituted compound, 1-acetylpyrene, in addition to the expected compounds, 6-acetyl- and 8-acetyl-1-bromopyrene. 7-Acetyl-1-bromopyrene was prepared via the acetylation of 2-acetylamino-1-bromo-4,5,9,10-tetrahydropyrene. The structures of the acetylbromopyrenes were assigned according to the two-dimensional NMR spectra.
Proton and Carbon-13 NMR Study of 1,1,4,4-Tetraphenyl- and 1,4-Diphenyl-1,3-butadiene Dianions in Solution. The Charge Distributions, Structural Features and Rotational Barriers of Phenyl Groups
Authors: Yokoyama Yukihiro , Takakura Yutaka , Sawasaki Takeshi , Takahashi Kensuke 
Published: July 2006

Abstract
The dicarbanions (1 and 2) produced from 1,1,4,4-tetraphenyl- and 1,4-diphenylbutadienes (1a and 2a) were investigated by means of the 1H and 13C NMR techniques. Large upfield shifts of the proton and carbon signals caused by the conversion of the hydrocarbons into the dianions were observed. Such shifts were used for evaluating the excess charge distributions in the dianions. From the coupling constants obtained it is concluded that the configuration of the central bond of the anion is the trans one for 1 but the cis one for 2. Thermodynamical parameters were obtained for the restricted rotation of the phenyl group of the lithium salt of 2.
The State of Polarization of Light Scattered by Anisotropic Spheroids
Authors: Sano Yoh 
Published: July 2006

Abstract
Using the light scattering theory of Rayleigh–Gans, theoretical expressions were derived for the state of polarization of light scattered by anisotropic spheroids in the case of linearly polarized incident light whose electric vector is inclined by ψ to the scattering plane. The azimuth of the ellipse of the light scattered is a function of the two scattering angles, θ and ψ, only and the scattered light is linearly polarized for linearly polarized incident light. The degree of polarization of the scattered light, which is defined as the ratio of the polarized component to the intensity of the scattered light, depends on the intrinsic anisotropy, pm; the relative refractive index of the spheroid to the solvent, m, and θ, together with the ψ angle. The degree of polarization varies from 1.0 to 0, depending strongly on pm, p and m. It has been suggested that the determination of the degree of polarization as a function of ψ and θ provides good information about the optically intrinsic anisotropy of the spheroid.
Electrochemistry of Tris(β-diketonato)ruthenium(III) Complexes at Platinum Electrodes in Nonaqueous Solutions and Substituent Effects on Their Reversible Half-Wave Potentials
Authors: Endo Akira , Hoshino Yoshimasa , Hirakata Keigo , Takeuchi Yasushi , Shimizu Kunio , Furushima Yuriko , Ikeuchi Haruko , Satô Gen P 
Published: July 2006

Abstract
The one-electron oxidation and reduction processes at platinum electrodes of a series of β-substituted and γ-substituted tris(β-diketonato)ruthenium(III) complexes are studied in acetonitrile, N,N-dimethylformamide, and nitromethane solutions, each containing 0.1 mol dm−3 (C2H5)4NClO4 at 25 °C. Syntheses of three new γ-substituted derivatives are described. Attempts to isolate the immediate product of the one-electron oxidation of [Ru(acac)3] in acetonitrile failed; bis(acetonitrile)bis(acetylacetonato)ruthenium(III) was obtained instead. Diffusion coefficients of the complexes in the acetonitrile medium are presented. The reversible half-wave potentials for the oxidation and the reduction in the acetonitrile medium depended linearly on the sum of the Hammett constants of the substituents (σp for the β-substituents and σm for the γ-substituents). Analysis of the dependence of the half-wave potentials on several kinds of substituent parameters suggests that the inductive effect is operative at both the β-positions and the γ-position, while the resonance effect is operative only at the β-positions.
Catalysis by Heteropoly Compounds. XII. Absorption Properties of 12-Tungstophosphoric Acid and Its Salts
Authors: Okuhara Toshio , Tatematsu Shin , Lee Kwan Young , Misono Makoto 
Published: July 2006

Abstract
The absorption of organic molecules into the bulk of H3PW12O40 and its salts was studied. Polar (or basic) molecules, such as alcohols and amines, were readily absorbed into H3PW12O40, but nonpolar hydrocarbons were not absorbed. The absorption depended not only on the polarity but also on the molecular size. The diffusion coefficients of the absorption of C1–C4 alcohols were of similar magnitudes, and were much smaller than that of the intracrystalline diffusion of methanol in ZSM-5. The amounts of absorbed molecules in H3PW12O40 tended to be in discrete values: that is, integral multiples of the number of protons (3, 6, etc.). This fact indicates that these polar molecules are protonated and form stable secondary structures throughout the bulk. It was confirmed in the case of methanol or ethanol that the transition between the states of 6 and 9 molecules/anion took place through the pressure changes. The absorptivity was greatly suppressed by the substitution of Cs+ for more than two H+, while the Na salts showed an absorptivity similar to that of H3PW12O40.
Cobalt(III) Complexes with Quadridentate Ligands. VIII. The Preparation and Properties of Cis-β1 and β2-Isomers of the Thiosalicylato(quadridentate amine)cobalt(III) Complexes
Authors: Yamamoto Yoshihisa , Yoshii Kayoko , Toyota Eiko , Konno Kazuko 
Published: July 2006

Abstract
cis-β1 and β2-Thiosalicylato(quadridentate amine)cobalt(III) complexes, cis-β1, β2-[Co(thiosal)L]X·nH2O (L: trien (2,2,2-tet), 3,2,3-tet; X: Cl, NO3), have been prepared from a reaction mixture of [CoCl2L]Cl·nH2O (L: trien, 3,2,3-tet), Ag2O, thiosalicylic acid (o-mercaptobenzoic acid), and 28% aqueous ammonia. Two geometrical isomers (cis-β1 and β2) of their complexes were separated by Dowex 50W-X2 column chromatography. The isomerization between the cis-β1 and β2-isomers is reversible in water at 40 °C. The IR spectra of these complexes showed four or five absorption bands in the 990–1100 cm−1 region and four absorption bands in the 3000–3300 cm−1 region. This indicates that these complexes assume the cis-β1-form. Their cis-β1 and β2 configurations have been established by their absorption and NMR spectra. The cis-β1 and β2-thiosalicylato(trien)cobalt(III) complexes have been tentatively assigned to the RR,SS diastereoisomer by their 1H NMR spectra. The color of solid state materials, solubilities in alcohols, isomerization at 40 °C, reaction in 60% nitric acid, absorption spectra, and chemical shift of Co–S–C carbon of the coordinated thiosalicylato ligand for the title complexes are different from those of the corresponding cis-β1 and β2-salicylato(quadridentate amine)cobalt(III) complexes, cis-β1, β1-[Co(sal)L]Cl·nH2O (L: trien, 2,3,2-tet, 3,2,3-tet, 3,3,3-tet), reported previously.
Photochemical Generation of Sn(III) in Hydrochloric Acid Solutions
Authors: Shinohara Nobuyoshi , Inoue Makoto 
Published: July 2006

Abstract
In the flash photolysis of Sn(II) in a deaerated hydrochloric acid solution, Sn(III) was produced. Sn(III) has an absorption maximum at 280 nm in a l mol dm−3 hydrochloric acid solution. In the flash photolysis of a deaerated Sn(IV) solution, intermediates of Sn(III) and Cl2− were produced. Transient absorption spectra of intermediates generated by the flashed Sn(IV) solutions were measured under various concentrations of dissolved oxygen. Since Sn(III) reacts with oxygen very rapidly, only Cl2− was confirmed in the oxygen-saturated Sn(IV) solution. In the flash photolysis of Sn(IV) solutions containing Sn(II), the yield of Sn(III) increased with an increase of the added Sn(II), due to the generation of Sn(III) by the reaction of Cl2− with Sn(II). It was found that only Sn(III) was produced in the irradiation of 5.0×10−4 mol dm−3 Sn(IV) solution containing Sn(II) at concentrations of more than ca. 7×10−5 mol dm−3. The reaction rate constant for the reaction of Sn(II) with Cl2− was estimated to be 8.9×108 mol−1 dm3 s−1. The mechanisms for the photochemical generation of Sn(III) are discussed.
Crystal Structures of [VO(sal-l-ala)(OCH3)(CH3OH)] (sal-l-ala=N-salicylidene-l-alaninate) and {[VO(sal-l-ala)]2O}2·2CH2Cl2, and the Catalytic Activity of These and Related Complexes on Asymmetric Oxidation of Methyl Phenyl Sulfide with t-Butyl Hydroperoxide
Authors: Nakajima Kiyohiko , Kojima Masaaki , Toriumi Koshiro , Saito Kazuo , Fujita Junnosuke 
Published: July 2006

Abstract
A reddish brown oxovanadium(V) complex, [VVO(sal-l-ala)(OCH3)(CH3OH)] (2a, sal-l-ala=N-salicylidene-l-alaninate) was formed by dissolving [VIVO(sal-l-ala)(H2O)] (1a) in methanol. Treatment of 2a with wet dichloromethane yielded deep blue crystals of {[VVO(sal-l-ala)]2O}2·2CH2Cl2 (3a). The structures of 2a and 3a have been determined by X-ray analyses. Crystal data are: [VO(sal-l-ala)(OCH3)(CH3OH)] (2a), monoclinic, C2, a=19.621(6), b=6.734(1), c=12.059(4) Å, β=117.72(2)° and Z=4. {[VO(sal-l-ala)]2O}2·2CH2Cl2 (3a), orthorhombic, P212121, a=19.938(4), b=23.854(5), c=11.526(2) Å, and Z=4. In 2a, the tridentate sal-l-ala ligand and a methoxide ion occupy the basal positions, and form distorted octahedral geometry around the vanadium(V) ion together with one methanol molecule (V–O distance: 2.384(4) Å) and the oxide ion of oxovanadium(V). The tetranuclear complex (3a) consists of two μ-oxo dinuclear vanadium(V) complexes, and each vanadium(V) ion has a distorted octahedral coordination. The Schiff base coordinates equatorially to each vanadium(V) ion, of which one axial site is occupied by O2− and the other is weakly linked to the carboxylate O atom of a nearby Schiff base (V–O distance: 2.34–2.56 Å). Octahedral coordination on each vanadium(V) is achieved by sharing an equatorial O2− ligand. The brown complexes, [VO(sal-l-aa)(OCH3)(CH3OH)] (2, sal-l-aa=N-salicylidene l-amino carboxylate) catalyze the oxidation of methyl phenyl sulfide with t-butyl hydroperoxide in dichloromethane at 4 °C to give (R)-methyl phenyl sulfoxide with optical yields (e.e.) of 8–14%.
Individuality of Amino Acid Residues in Protected Peptides. Conformational and β-Sheet Structure-Disrupted Behaviors of Resin-Bound Peptides
Authors: Narita Mitsuaki , Isokawa Shizuko , Honda Shinya , Umeyama Hiroshi , Kakei Hideaki , Obana Satoshi 
Published: July 2006

Abstract
The conformational behavior of cross-linked polystyrene resin-bound peptides swollen in CH2Cl2 was analyzed using IR absorption spectroscopy. All of the resin-bound peptides easily aggregated with each other through intermolecular hydrogen bonding to form a β-sheet structure. The disruption of the β-sheet structure was further investigated by a solvent titration method in order to clarify the individuality of amino acid residues. At a pentapeptide level, the β-sheet structure was easily disrupted by the addition of a small amount of HFIP. On the other hand, at a larger peptide level, the disrupted behavior of the β-sheet structure was different from each other according to the amino acid composition. Based on the view that the secondary structure of globular proteins reflects the individuality of the 20 kinds of amino acid residues in proteins, we attempted to evaluate how easily the β-sheet structure of peptides is disrupted by HFIP using the average conformation values: 〈Pα〉, 〈Pβ〉, and 〈Pc〉. As a result, the β-sheet structure-disruption of peptides having a low potential for a β-sheet→helix transformation as well as for the randomness was difficult by adding increasing amounts of HFIP. On the other hand, that of the peptides having a 〈Pc〉 value larger than 0.85 and/or a high potential for the β-sheet→helix transformation proceeded smoothly upon adding increasing amounts of HFIP.
Selectivities of Aromatic Methyl Metalation. Unexpectedly Strong Interactions of Carbanions with Aromatic Rings
Authors: Inagaki Satoshi , Imai Takeo , Mori Yoshio 
Published: July 2006

Abstract
The site selectivities of the metalation reactions of dimethylnaphthalenes and dimethylanthracenes followed by MeOD quenching were investigated experimentally and theoretically. The 2(3)-methyl groups were found to be more effectively metalated than expected from the LUMO amplitudes of the aromatic rings. The MNDO calculations suggested that the naphthylmethyl and anthrylmethyl anions are not the aromatic rings perturbed by the carbanions, but the significantly different conjugated rings doubly bonded to the exocyclic carbon atoms. The unexpectedly strong interactions of the carbanion centers with the aromatic rings can account for the discrepancies between the selectivities and the LUMO amplitudes.
Physicochemical Stabilization of Lipid Microspheres by Coating with Polysaccharide Derivatives
Authors: Carlsson Anders , Sato Toshinori , Sunamoto Junzo 
Published: July 2006

Abstract
A methodology to improve lipid microspheres (LM) as a carrier for lipophilic drugs and their physicochemical properties are described. The LM were prepared from glycerides, glycerol, and phospholipids. The method involves coating of the surface of the LM with a naturally occurring or chemically modified polysaccharide. Special emphasis will be made on cholesterol-bearing pullulan and amylopectin. This is the same approach as that adopted for the stabilization of liposomes. Turbidity measurement revealed that the coating effectively depressed the Ca2+-induced aggregation of the LM. From fluorescence polarization measurements, it was concluded that the fluidity of the LM surface decreased with the polysaccharide coating. Furthermore, the coating effect was investigated by zeta-potential measurements. The coating reduced the negative zeta-potential of the LM to an apparently neutral value.
Effects of Substituents and Solvents on the Electronic Spectra of 9,10-Dihydro-9,10-o-benzenoanthracene-1,4-diones: Intramolecular Charge Transfer
Authors: Kitaguchi Nobuya 
Published: July 2006

Abstract
Electronic spectra of substituted 9,10-dihydro-9,10-o-benzenoanthracene-1,4-diones (triptycenequinones) in various solvents and that of benzo- and dibenzotriptycenequinones were investigated in this paper. Intramolecular charge-transfer (CT) bands ware observed in triptycenequinone system as a result of intramolecular interaction between benzene ring and benzoquinone moiety. Substituents on the benzene rings strongly affected the CT bands. Electron-donating groups gave absorption maxima at long wavelength. Naphthalene ring gave similar but stronger CT bands than benzene ring. Hammett σ+ value of substituents gave good linear relationship with the energy of the CT bands. Calculations of reduced charge matrix of triptycenequinones by extended Hückel theory showed that the charge of aromatic ring(s) were transferred to benzoquinone moiety accompanying HOMO–LUMO excitation. Especially, absorption maxima of the methyl-substituted triptycenequinones gave good correlation with the amounts of charge transferred from benzene ring to benzoquinone moiety. These analysis confirmed clearly CT character of the absorption maxima of triptycenequinones. However, solvent effect of these CT bands maxima is not so clear as the substituent effect.
Facile Construction of Optically Active 1,3-Diols. Synthesis of (2S,4R)-7-Octene-2,4-diol and endo-(1S,3S,5R)- and exo-(1R,3S,5S)-1,3-Dimethyl-2,9-dioxabicyclo[3.3.1]nonane
Authors: Chikashita Hidenori , Kittaka Eiji , Kimura Yasunori , Itoh Kazuyoshi 
Published: July 2006

Abstract
A short and stereoselective asymmetric synthesis of (2S,4R)-7-octene-2,4-diol (a key intermediate in the Bartlett synthesis of nonactic acid) and two stereoisomers of a biologically active substance isolated from Norway spruce infested by ambrosia beetle, endo-(1S,3S,5R)- and exo-(1R,3S,5S)-1,3-dimethyl-2,9-dioxabicyclo-[3.3.1]nonane, was effectively accomplished in three and four reaction steps, respectively, by starting with easily obtainable (S)-1-(1,3-dithian-2-yl)-2-propanol by baker’s yeast asymmetric reduction. The main strategy was based on a facile construction of optically active β-hydroxy ketones via alkylation of the dianion of (S)-1-(1,3-dithian-2-yl)-2-propanol with alkyl halides, followed by their stereoselective reductions.
Stereoselective β-C- and β-S-Glycosylation of 2-Deoxyribofuranose Derivatives Controlled by the 3-Hydroxy Protective Group
Authors: Ichikawa Yuh-ichiro , Kubota Hideki , Fujita Ken’ichi , Okauchi Tatsuo , Narasaka Koichi 
Published: July 2006

Abstract
β-C-2-Deoxyribofuranosides and β-S-2-deoxyribofuranosides are prepared stereoselectively from 1-O-acetyl-5-O-benzyl-3-O-[2-(methylsulfinyl)ethyl]-2-deoxy-d-erythro-pentofuranose or the corresponding 3-O-(2-pyridyl-methyl)pentofuranose N-oxide by the reaction with silyl enol ethers or trimethlsilyl sulfides in the presence of a Lewis acid.
New Synthesis of 2-Oxo-3-alkenylphosphonates and Hetero Diels–Alder Reactions with Vinyl Ethers Leading to 5-Substituted 2-Phosphiny 1-2-cyclohexen-1-ones
Authors: Wada Eiji , Kanemasa Shuji , Tsuge Otohiko 
Published: July 2006

Abstract
A new method of synthesizing phosphinyl-substituted enones, 2-oxo-3-alkenylphosphonates, is developed via the dianion of diethyl 2-oxopropylphosphonate. The enones serve as hetero dienes in thermal reactions with vinly ethers producing 2-alkoxy-6-(phosphinylmethyl)-3,4-dihydro-2H-pyrans. Acid-catalyzed cleavage of these cycloadducts is followed spontaneously by internal condensation furnishing 2-phosphinyl-2-cyclohexen-1-one derivatives.
Stereochemical Control in Microbial Reduction. 8. Stereochemical Control in Microbial Reduction of β-Keto Esters
Authors: Nakamura Kaoru , Kawai Yasushi , Oka Shinzaburo , Ohno Atsuyoshi 
Published: July 2006

Abstract
Stereochemistry of the reduction of β-keto esters with bakers’ yeast is controlled by the addition of a certain α,β-unsaturated carbonyl compound (or its reduced form). Glucose also exerts the same effect. The additives tend to shift the stereochemistry of the reduction toward the production of d-hydroxy ester. Namely, methyl 3-oxopentanoate and ethyl 3-oxo-6-heptenoate were reduced to the corresponding d-hydroxy esters with excellent stereoselectivities and chemical yields. The enones are supposed to inhibit the enzymes that produce the l-hydroxy ester, whereas glucose plays a role to activate the enzymes that produce the d-hydroxy ester.