bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Protolytic Behavior of Ligands on Formation Rates of Mono-complexes of Nickel(II) Ion with 2,2′-Bipyridine and 1,10-Phenanthroline in Aqueous Solution
Authors: Ando Isao , Nishijima Shigeyoshi , Ujimoto Kikujiro , Kurihara Hirondo 
Published: July 2006

Abstract
The mono-complex formation of nickel(II) ion with 2,2′-bipyridine(bpy) and 1,10-phenanthroline (phen) was studied in aqueous solution by means of a stopped-flow method. The apparent complex formation rates of the Ni(II)–bpy and Ni(II)–phen complexes depended on the pH of the solution. The rate constants of the mono-complex formation with the ligand in the free base form, kf, and that with the monoprotonated ligand, kfh, were evaluated from the rate-[H+] profiles in the region of high hydrogen ion concentration where the pseudo-equilibrium of acid dissociation of the ligands was attained during the complex formation. The rate constants determined for the Ni(II)–phen were kf=(2.6±0.3)×103 mol−1 dm3 s−1 and kfh=2.4±0.3 mol−1 dm3 s−1, which are practically the same as those reported elsewhere. On the other hand, the rate constants for the Ni(II)–bpy were kf=(5.3±1.2)×103 mol−1 dm3 s−1 and kfh=5.0±2.6 mol−1 dm3 s−1, which are quite different from the values reported by other researchers. The validity of the present data was discussed in terms of slow proton-transfer reactions of the ligands.
Macrocyclic Enzyme Model System. Kinetic Activity of [20]Paracyclophane Bearing 1,4-Dihydronicotinamide and 2-Pyridinecarboxylic Acid Moieties as Effected by Zinc Ion
Authors: Murakami Yukito , Aoyama Yasuhiro , Kikuchi Jun-ichi 
Published: July 2006

Abstract
As regards the effect of zinc(II) ion on the reduction of hexachloroacetone, the kinetic activity of a [20]paracyclophane (PCP) bearing 1,4-dihydronicotinamide (HNA) and 2-pyridinecarboxylic acid (Py) moieties, HNA–PCP–Py, has been investigated as an alcohol dehydrogenase model in reference to that of PCP–HNA in the light of their metal-coordination behavior. The reduction ability of PCP–HNA was significantly lowered as it underwent complex formation with zinc. On the other hand, HNA–PCP–Py showed an apparent rate maximum in a relatively lower concentration range of ZnCl2. The kinetic behavior was analyzed on the basis of the formation of two kinds of zinc complexes of HNA–PCP–Py: the 1:1 complex (Remark: Graphics omitted.), in which both Py and HNA moieties are simultaneously coordinated to the same zinc ion, showed a decreased reactivity relative to metal-free HNA–PCP–Py; while the 2:1 complex (HNA–PCP–Py–ZnII–Py–PCP–HNA), in which HNA is free from metal-coordination, exercised a much enhanced activity, 7 times as reactive as metal-free HNA–PCP–Py. A plausible reaction mechanism for the enhanced reactivity has been discussed.
Substitution of Cyano Group by Hydroxyalkyl Group and of Ring Hydrogen by Alkoxyl Group in UV-Irradiation of 2-Pyridinecarbonitrile in Alcohols
Authors: Sugimori Akira , Furihata Toshikazu , Mikayama Shigeyuki , Yoshida Makiko , Nakanishi Yasuo 
Published: July 2006

Abstract
The UV-irradiation of 2-pyridinecarbonitrile(1) in methanol and in ethanol brings about the replacement of the cyano group by the hydroxyalkyl groups and the replacement of the ring hydrogen by the alkoxyl group. Free base-form of 1 in ethanol undergoes exclusively photo-hydroxyethylation, while the pyridinium form of 1 in ethanol undergoes both photo-hydroxyethylation via a singlet excited state and -ethoxylation via a singlet-excited state complex, which is quenched by the electron transfer from the aromatic hydrocarbons to the excited complex.
Reaction of 1-Ethyl-3-methyl-4-imidazoline-2-thione with Methyl Iodide. Kinetic and Thermodynamic Aspects
Authors: Yamada Tetsuya , Kondo Yasuhiko , Kusabayashi Shigekazu 
Published: July 2006

Abstract
The reaction of 1-ethyl-3-methyl-4-imidazoline-2-thione with methyl iodide followed simple second order kinetics in polar solvents, whereas in less polar solvents the reverse process made a significant contribution to the overall rate. The solvent effects on the forward rate constant were linearly related to those on the rate of the reaction of tetramethylthiourea with methyl iodide. A plot of ΔV0\eweq vs. Δ\barV° was linear with a slope of 0.33. From the volume changes and enthalpy changes measured, three transition state indices, (Δ2V\eweq⁄Δ2\barV°), nT and α were determined in acetonitrile, ca. 0.33, 0.32, and 0.41, respectively.
Synthesis of Sugar Derivatives of Tervalent Phosphorus Compounds and Their Application to Homogeneous Asymmetric Hydrogenation
Authors: Yamashita Mitsuji , Hiramatsu Koji , Yamada Manabu , Suzuki Nobuyoshi , Inokawa Saburo 
Published: July 2006

Abstract
Diphenylphosphine and diphenylphosphinite derivatives of sugars such as methyl 6-deoxy-4-C-(diphenylphosphino)-2,3-O-isopropylidene-α-l-talopyranoside, methyl 4-O-(diphenylphosphino)-2,3-O-isopropylidene-α-l-rhamnopyranoside, methyl 4-C,4-O-(diphenylphosphino)-2,3-O-isopropylidene-α-l-talopyranoside, 6-deoxy-6-C-(diphenylphosphino)-1,2:3,5-di-O-isopropylidene-α-d-glucofuranose, and 6-O-(diphenylphosphino)-1,2:3,4-di-O-isopropylidene-α-d-galactopyranose were synthesized by the reaction of diphenylphosphine-sodium dihydrobis(2-methoxyethoxy)aluminate (SDMA) and/or diphenylphosphinous chloride-triethylamine with sugar derivatives. Homogeneous asymmetric hydrogenations of several prochiral olefins (α-acetylaminocinnamic acid, methyl α-acetylaminocinnamate, α-benzoylaminocinnamic acid, itaconic acid, and tiglic acid) were carried out using rhodium(I) catalysts with the tervalent chiral phosphorus derivatives of sugars. The highest optical yield for all the five substrates was obtained when di-μ-chloro-bis(cyclooctadiene)dirhodium(I) and 6-O-(diphenylphosphino)-1,2:3,4-di-O-isopropylidene-α-d-galactopyranose were used. The advantages of this method are the simplicity in the synthesis of the chiral phosphorus compound and the comparatively high optical yield in the asymmetric hydrogenation of olefins.
Mechanism of Dye-sensitized Photooxidation of Tryptophan, Tryptamine, and Their Derivatives. Singlet Oxygen Process in Competition with Type I Process
Authors: Inoue Kenzo , Matsuura Teruo , Saito Isao 
Published: July 2006

Abstract
Photosensitized oxidations of tryptophan (Trp), tryptamine, and their derivatives were investigated with a variety of sensitizers. Rose Bengal sensitized photooxidations proceed exclusively via Type II mechanism (singlet oxygen mechanism), whereas for thionine-sensitized photooxidations both Type I (nonsinglet oxygen mechanisms) and Type II mechanisms are operative under a given set of conditions. Rate constants of reaction, in units of 106 M−1 s−1, were determined to be 3 for Trp, 4 for tryptophan methyl ester, 4 for Nb-acetyltryptophan methyl ester, 9 for tryptamine, and 7 for Nb-methoxycarbonyltryptamine in the Rose Bengal-sensitized photooxidations. These values are in good agreement with those obtained from reactions with chemically generated singlet oxygen. Quenching rate constants are somewhat larger than reaction rates constants, indicating that the quenching process is the major path for the interaction of singlet oxygen with these indolic substrates. Oxidation products in chemically generated singlet-oxygen reaction of Trp are compared with those obtained from dye-sensitized photooxidations.
A New and Convenient Synthetic Method for Cyclopropyl Phenyl Sulfides
Authors: Tanaka Kazuhiko , Uneme Hideki , Matsui Shuichi , Kaji Aritsune 
Published: July 2006

Abstract
The reactions of a variety of 1,3-bis(phenylthio)propanes with butyllithium have been shown to produce cyclopropyl phenyl sulfides in good to high yields. A new and convenient in situ preparation of 1-lithiocyclopropyl phenyl sulfide can be readily carried out by treating 1,3-bis(phenylthio)propane with 2 equiv. of butyllithium at 0 °C in THF. The reaction with electrophiles proceeds in good yield. O-Aryl and O-alkyl S-cyclopropyl dithiocarbonates also can be prepared in good yields. 1,2-Bis(phenylthio)ethane was converted to phenyl vinyl sulfide on treatment with butyllithium, while 1,4-bis(phenylthio)butane was recovered unchanged by a similar treatment.
Alkylation of Benzothiazolines and the Stevens Rearrangement of the Resulting 2,3,3-Trisubstituted Benzothiazolinium Salts
Authors: Akiba Kin-ya , Ohara Yoshio , Inamoto Naoki 
Published: July 2006

Abstract
Alkylation of 2-substituted 3-methyl- or 3-ethylbenzothiazolines with Meerwein reagents gave 2-substituted 3,3-dialkylbenzothiazolinium tetrafluoroborates (3). The configuration of two alkyl groups on the nitrogen was assigned by NMR spectra and NOE measurement. In the Stevens rearrangement of 3 with lithium diisopropylamide ethyl group showed a much larger migratory aptitude (Et:Me≥20 :1) than methyl group irrespective of the configuration of 3, and cyclic ammonium ylide with planar π-type carbanion was proposed as an intermediate. 3 suffered nucleophilic attack at the ring sulfur atom by butyllithium to afford a ring-opened ammonium ylide, which collapses to a radical pair to give unusual Stevens rearrangement product, where o-alkylthiophenyl group migrated selectively in preference to alkyl group, because of stabilization by participation of o-alkylthio group.
Ylide-Metal Complexes. VI. The Preparation and Properties of IVA-group Metal (Ge, Sn, Pb) Complexes of Alkylidenetriphenylphosphoranes
Authors: Yamamoto Yoshihisa 
Published: July 2006

Abstract
(Triphenylphosphonium alkylide)triphenylmetal chloride [(C6H5)3\overset+PCHR–M(C6H5)3]Cl− (R: H, Me, i-pr; M: Ge, Sn, Pb) and (triphenylphosphoniumalkylide)metal chloride [(C6H5)3\overset+PCHR]nMCln−, (M=Ge,n= 4; M=Pb, n=2) have been isolated from a reaction mixture of alkylidenetriphenylphosphoranes and IVA-group metal compounds. The ylide in [(C6H5)3\overset+PCH2–Pb(C6H5)3]Cl− is bonded to the lead atom through the carbanionic donor atom.
Regioselective Reaction of Allylic Carbanion Derived from 1-Phenylthio-2-octene with Conjugated Cyclopentenone Derivative and Synthesis of Prostaglandin E1
Authors: Nokami Junzo , Ono Toshio , Iwao Atsunori , Wakabayashi Shoji 
Published: July 2006

Abstract
The reaction of the allylic carbanion derived from 1-phenylthio-2-octene with conjugated cyclopentenone derivatives in the presence of hexamethylphosphoric triamide (HMPA) regioselectively gave the 1,4 adduct at the α carbon of the allylic sulfide. The reaction was employed for the synthesis of prostaglandin E1.
Origins and Spin Dependence of Near Infrared Magnetic Circular Dichroism of Iron(III) Hemoproteins
Authors: Yamamoto Takao , Nozawa Tsunenori , Kobayashi Nagao , Hatano Masahiro 
Published: July 2006

Abstract
Temperature variation experiments on near infrared magnetic circular dichroism spectra (700–2000 nm) have demonstrated that metmyoglobin (iron(III) myoglobin) cyanide and metmyoglobin fluoride derivatives which are typical low and high spin iron(III) heme complexes, respectively, exhibit the Faraday C term and the Faraday C and A terms, respectively. The results are consistent with theoretical predictions based on the assignment that the near infrared bands of the iron(III) heme complexes are attributable to the charge-transfer transitions from the occupied a1 and a2 π orbitals to the vacant iron dπ (dxz, dyz) orbitals in a C4v notation.
Viscosities of Aqueous Solutions of Sodium Alkanoates
Authors: Miyajima Koichiro , Sawada Masahiro , Nakagaki Masayuki 
Published: July 2006

Abstract
Viscosities of aqueous solutions of sodium salts of formic acid, acetic acid, propionic acid, and butyric acid were measured in the concentration range 0.01–0.1 mol dm−3 at 15, 25, and 35°C For formate ion, values of Bst, the increment of viscosity B-coefficient arising from structural change of water, and of (dBion⁄dT), the temperature dependence of ionic B-coefficient, are both nearly zero, indicating that formate ion is neither a structure maker nor a structure breaker. For the alkanoate ions the signs of Bst and (dBion⁄dT) are positive and negative, respectively. From these facts, alkanoate ions may be concluded to be hydrophobic structure making ions.
Motion of Methylammonium Ions in Solid CH3NH3NO3 and CH3NH3SCN Studied by 1H NMR
Authors: Ishida Hiroyuki , Ikeda Ryuichi , Nakamura Daiyu 
Published: July 2006

Abstract
The proton spin-lattice relaxation time T1 at 20 MHz and the second moment of 1H NMR absorptions at 40 MHz were determined at various temperatures between 77 and 300 K for CH3NH3NO3 and CH3NH3SCN, and their partially deuterated analogs, CH3ND3NO3 and CH3ND3SCN. A phase transition was located at 242 K for CH3NH3SCN. The fully protonated compounds yielded two T1 minima, the low- and high-temperature one of which could be attributed to the reorientation of the CH3 and NH3+ groups, respectively, of the cation about the C–N bond axis. The activation energy was evaluated for these motional modes.
Intercalation Compounds of FeOCl. Systematics of Amine Containing Lewis Base Intercalants
Authors: Maeda Yonezo , Yamashita Miyako , Ohshio Hiroki , Tsutsumi Naoto , Takashima Yoshimasa 
Published: July 2006

Abstract
New intercalated compounds of FeOCl and aniline derivatives were synthesized by soaking FeOCl in ethanol solution containing Lewis base intercalants. Only those Lewis base intercalants whose acid-dissociation constant is greater than 5 intercalate into the lattice of FeOCl. The acid-strength of the solvent is important for the formation of an intercalation compound. The intercalates of iron(III) chloride oxide FeOCl(G)1⁄n have been characterized by elemental analysis, powder pattern of X-ray diffraction, Fe-57 Mössbauer and infrared spectroscopies. The research on expansion of the b-axis of the unit cell and IR data confirm the location of the “guest” molecule within the van der Waals layer or the FeOCl lattice. Effective vibrating mass and lattice temperature derived from the Mossbauer spectra are affected by chemical bonding in the first coordination sphere of the iron atom.
A Thermodynamic Study of the Synergistic Solvent Extraction of a Series of Zinc(II) and Cadmium(II) Complexes
Authors: Yamada Etsu , Nakayama Eiichiro , Kuwamoto Tooru , Fujinaga Taitiro 
Published: July 2006

Abstract
The extraction of zinc and cadmium using chloroform and benzene solutions constaining diphenylcarbazone (DPC=Hdpc), either alone or combined with pyridine(py) or 1,10-phenanthroline(phen), was studied thermodynamically. The formation constants were measured as functions of the temperature in order to ascertain the free energy, enthalpy, and entropy changes. The thermodynamic parameters support a proposed mechanism for the synergism of zinc in which the coordination number of the zinc ion expands with formation of Zn(dpc)2S, where S is pyridine or 1,10-phenanthroline. On the other hand, the thermodynamic values for the synergistic reaction of cadmium support a mechanism in which pyridine or 1,10-phenanthroline replaces the residual waters of hydration in the first coordination sphere of cadmium.
Coordination Structure of Cu2+ Ion in Highly Concentrated Aqueous CuBr2 Solution, Determined by X-Ray Diffraction Analysis
Authors: Ichihashi Mitsuyoshi , Wakita Hisanobu , Mibuchi Takeharu , Masuda Isao 
Published: July 2006

Abstract
The solute structure of concentrated aqueous copper(II) bromide solutions was determined by the analysis of the radial distribution curves of X-ray diffraction measured on the solutions with varying concentrations, 4.364–1.016 mol dm−3. The mixed-ligand aquabromocopper(II) complexes were found to be present in these solutions, and to have a distorted octahedral geometry. The Cu2+ ion was coordinated with Br− ions at the equatorial sites whose bond lengths were shorter than the axial sites. The interatomic distances of the equatorial Cu–Br and Cu–OH2 bonds were, respectively, 2.42–2.46 and 1.96–1.99 Å, and that of the axial Cu–OH2 bond, 2.37–2.51 Å. The average coordination number of Br− ions in the nearest neighbor of the Cu2+ ion increased from 0.33 to 1.31 as the concentration of CuBr2 increased from 1.016 to 4.364 mol dm−3. Even in the 4.364 mol dm−3 solution, which was nearly saturated, the coordination of the Br− ion at the axial site was not evidenced. In the 1.474 mol dm−3 CuBr2 solution dissolved in an aqueous 6.923 mol dm−3 HBr solution, the tetrabromocopper(II) complex species was proposed to exist in a flattened tetrahedral form, wherein the Cu–Br distance was 2.41 Å.
Preparation, Resolution, and Spectroscopic Properties of Bis[(2-aminoethyl)diphenylphosphine]- and (Ethylenediamine)[1,2-bis(diphenylphosphino)ethane]–Cobalt(III) Complexes of Acetylacetonate, Malonate, Oxalate, and Carbonate Ion
Authors: Atoh Masamichi , Kinoshita Isamu , Kashiwabara Kazuo , Fujita Junnosuke 
Published: July 2006

Abstract
New complexes of the [Co(O–O)(edpp)2]- and [Co(O–O)(en)(dppe)]- type were prepared from trans(Cl, Cl)[CoCl2(edpp)2]ClO4 and trans-[CoCl2(en)(dppe)]ClO4·H2O, respectively, where O–O is an acetylacetonate, malonate, oxalate, or carbonate ion, and en, edpp, and dppe denote ethylenediamine, (2-aminoethyl)diphenylphosphine, and 1,2-bis(diphenylphosphino)ethane, respectively. All the complexes of the former type gave two geometrical isomers of trans(P, P) and trans(P, N) configurations, which were assigned on the basis of the 1H and 3C NMR, and electronic absorption spectra. No trans(N, N) isomers were formed. The yields of the trans(P, N) isomers were always larger than those of the corresponding trans(P, P) isomers. With the decreasing ring members of the O–O chelates, the yield of the trans(P,P) isomer decreases, the trans(P,P)-carbonato complex being formed in trace amounts. The first absorption bands of the trans(P,P) isomers have very strong intensity as compared with those of the corresponding trans(P,N) and the dppe complexes. All the complexes except for [Co(O–O)(en)(dppe)]+ (O–O=malonate and oxalate ions) were resolved by the chemical or SP-Sephadex C-25 column chromatographic method, and the circular dichroism spectra were recorded and compared with those of related complexes.
Reaction Process of Titanium Tetrachloride with Ammonia in the Vapor Phase and Properties of the Titanium Nitride Formed
Authors: Saeki Yuzo , Matsuzaki Ryoko , Yajima Akimasa , Akiyama Masayo 
Published: July 2006

Abstract
The reaction products of gaseous TiCl4 with ammonia were TiCl4·5NH3 at 200 °C, TiCl4·5NH3, TiClN, and NH4Cl at 250–400 °C, TiCl4·5NH3, TiClN, TiNx, and NH4Cl at 450–650 °C, TiNx and NH4Cl at 700–1000 °C, and TiNx, NH4Cl, and HCl at 1100–1400 °C. The N/Ti atomic ratio, x, of the TiNx formed was 1.21 at 700 °C, 1.16 at 800 °C, 1.13 at 900 °C, and 1.10 above 1000 °C. The lattice constants of the TiNx formed are shown. The reaction process can be represented as follows: The reaction of gaseous TiCl4 with ammonia occurs first to form TiCl4·5NH3. Above ca. 220 °C, the TiCl4·5NH3 decomposes to TiClN. Above ca. 430 °C, the TiClN reacts with ammonia to form TiNx. Above ca. 1100 °C, in addition to these reactions, the reaction of TiCl2, formed by the reduction of TiCl4 with hydrogen resulting from the thermal dissociation of ammonia, with ammonia occurs to form TiNx. On heating the TiNx, formed by the vapor-phase reaction, at temperatures higher than 500 °C in an argon atmosphere, the value of x decreased and became close to that of the stoichiometric nitride, being 1.02 at 900–1100 °C.
Direct Synthesis of Cyclic Carbonates in the Presence of Organometallic Compounds. Catalyses by Systems from IVA, VA, and VIA Group Compounds and Lewis Base
Authors: Nomura Ryoki , Kimura Masahiro , Teshima Satoshi , Ninagawa Akira , Matsuda Haruo 
Published: July 2006

Abstract
In the cycloaddition of carbon dioxide to oxiranes to form cyclic carbonates in the presence of organometallic halides of group IVA, VA, and VIA, catalytic activities of organometallic halides are in the order Sb&gt;Te&gt;Sn&gt;&gt;Bi, Ge, and Si. An improvement of their catalytic activities is achieved by addition of an equimolar amount of Lewis base. In binary catalyst systems, the order of catalytic activities is in the order Sn&gt;Te&gt;Sb&gt;&gt;Bi, Ge, and Si. Organotin halide–base systems show the highest catalytic activity.
Preparation of Alkylnickel(II)–Phosphine Complexes by Reactions of Ni(acac)2 with Alkylaluminums in the Presence of Tertiary Phosphine
Authors: Yamamoto Takakazu , Takamatsu Masakatsu , Yamamoto Akio 
Published: July 2006

Abstract
Four new alkylnickel(II)–phosphine complexes, NiR2(PR′3)2 (R=CH3, C2H5; PR′3=triethylphosphine (PEt3), tributylphosphine (PBu3), 1,2-bis(diphenylphosphino)ethane(dpe)) and Ni(CH3)(acac)(PEtPh2) (PEtPh2=ethyldiphenylphosphine), have been prepared by reactions of Ni(acac)2 with AlR2(OC2H5) in the presence of phosphine ligands.
Syntheses and Properties of Di-, Tri-, and Tetracyclopropyltropylium and Di- and Tri-t-butyltropylium Ions
Authors: Komatsu Koichi , Takeuchi Ken’ichi , Arima Makoto , Waki Yoshinori , Shirai Shuzo , Okamoto Kunio 
Published: July 2006

Abstract
The polysubstituted tropylium ions having cyclopropyl or t-butyl groups at the ring positions with the least steric hindrance, i.e. 1,3- and 1,4-dicyclopropyltropylium, 1,3- and 1,4-di-t-butyltropylium, 1,3,-5-tricyclopropyl- and 1,3,5-tri-t-butyltropylium and 1,2,4,6-tetracyclopropyltropylium ions (4), were synthesized, and their properties were compared with the known monosubstituted and unsubstituted cations. The 1H and 13C NMR spectra for the cyclopropyl derivatives and the 13C NMR spectra for the t-butyl derivatives exhibited a gradual upfield shift for the seven-membered ring signals upon consecutive substitution. Accordingly, for the t-butyl derivatives, the pKR+ values were found to linearly increase upon introduction of each substuent; for the cyclopropyl derivatives, a larger extent of the pKR+ increase was observed with each substitution, and the pKR+ of the tetrasubstituted derivative 4 amounted to 9.10 (50% aq MeCN, 25 °C), the highest value presently known for the hydrocarbon cations having the tropylium unit, although the cumulative substituent effect deviated from the linear additivity correlation as the substituent number increased. The substituent effects upon the reduction potential and the CT transition energy (pyrene as a donor) were also examined and shown to have the same tendency in general.
Reactivities of Stable Rotamers. X. Reactions of 9-(2-Formyl-1-naphthyl)fluorene Rotamers and Related Compounds
Authors: Saito Ryo , Oki Michinori 
Published: July 2006

Abstract
Rotational barrier (ap→sp) in 9-(2-formyl-1-naphthyl)fluorene was determined: ΔH\eweq24.0 kcal/mol and ΔS\eweq−7.9 e.u. Oxidation of the aldehyde with chromium(VI) oxide was extremely slow in the ap form, whereas it proceeded smoothly in the sp form. As models of the 2 steps involved in the aldehyde oxidation, oxime formation of the aldehyde and oxidation of related alcohols were carried out to conclude that the second elimination step in the aldehyde oxidation is slow in the ap form because of the steric effect. Dehydration of the oxime of the aldehyde exhibited a large ksp/kap value as well. Sodium tetrahydridoborate reduction and Grignard additions of the aldehyde were also carried out to show that the former gave a large ksp/kap value whereas the latter exhibited rather a small ksp/kap. The implication of the results is discussed.
The Enantioselective Michael Addition of Thiols to Cycloalkenones by Using (2S, 4S)-2-Anilinomethyl-1-ethyl-4-hydroxypyrrolidine as Chiral Catalyst
Authors: Suzuki Keisuke , Ikegawa Akihiko , Mukaiyama Teruaki 
Published: July 2006

Abstract
Catalytic asymmetric addition of thiols to 2-cycloalkenone was studied by using the chiral amino alcohols, derived from l-hydroxyproline or (S)-proline, as base catalysts. Detailed investigation was carried out on the effects of the structure of the catalyst, the reaction medium, the temperature, and the concentration on the enantioselectivity. Good optical yields (47–88%) were achieved by the reaction of arenethiols and 2-cyclohexen-1-one in toluene at −5 °C, by using the catalyst (2S, 4S)-2-anilinomethyl-1-ethyl-4-hydroxypyrrolidine.