研究者詳細 - 菅　誠治

論文 - 菅　誠治

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2-pyridylsilyl group as a multifunctional 'phase tag' for solution phase synthesis

Jun ichi Yoshida, Kenichiro Itami, Koichi Mitsudo, Seiji Suga

Tetrahedron Letters 40 ( 17 ) 3403 - 3406 1999年4月

掲載種別：研究論文（学術雑誌）

2-Pyridyldimethylsilyl (2-PyMe2Si) group was found to serve as effective 'phase tag' for acid-base extraction for solution phase synthesis. Acid-base extraction of octyl(2-pyridyl)dimethylsilane gave rise to 98% recovery. The introduction of 2-PyMe2Si group to organic molecules was easily accomplished by Rh catalyzed hydrosilylation of alkenes with 2- PyMe2SiH. The removal of 2-PyMe2Si group was achieved by the oxidation with H2O2/KF (Tamao oxidation). In order to demonstrate the utility of 2- PyMe2Si group as a 'phase tag', a sequential multi-step transformation was conducted. The products of each steps were easily isolated by acid-base extraction, and were sufficiently pure for the direct use in the next step of the sequence.

DOI： 10.1016/S0040-4039(99)00474-8

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General and efficient method for the synthesis of alkoxymethylsilanes

Seiji Suga, Keiko Miyamoto, Mitsuru Watanabe, Jun Ichi Yoshida

Applied Organometallic Chemistry 13 ( 6 ) 469 - 474 1999年

掲載種別：研究論文（学術雑誌）

Although alkoxymethylsilanes serve as useful building blocks, various efforts to synthesize them by substitution reaction with an alkoxide ion at the carbon adjacent to the silicon failed. To solve this synthetic problem a new route which is very simple to perform was developed. Bromination of (methoxymethyl)trimethylsilane by using N-bromosuccinimide/2,2′-azobisisobutyronitrile (NBS/AIBN) was followed by a substitution by alcohols in the presence of triethylamine to give the corresponding [alkoxy-(methoxy)methyl]trimethylsilanes. These acetals can be used directly for the next reduction with di-isobutylaluminium hydride (DIBAL-H) or Et3SiH/BF3·OEt2 to give alkoxymethylsilanes in good to moderate yields. The success of the substitution reaction with the alcohols suggests that the mechanism is of somewhat SN1 by nature and formation of the cationic intermediate seems to release the steric hindrance around the carbon, allowing the attack of alcohols. Copyright © 1999 John Wiley & Sons, Ltd.

DOI： 10.1002/(SICI)1099-0739(199906)13:6<469::AID-AOC872>3.0.CO;2-A

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2-(2-pyridyl)ethylsilyl group as a new class of electroauxiliary. Fine tuning of the electron transfer driven reactions by the dynamic coordination to silicon

Jun Ichi Yoshida, Seiji Suga, Ken Ichi Fuke, Mitsuru Watanabe

Chemistry Letters ( 3 ) 251 - 252 1999年

掲載種別：研究論文（学術雑誌）

The introduction of 2-(2-pyridyl)ethyl group on silicon decreases the oxidation potentials of silyl-substituted heteroatom compounds. The molecular orbital calculations indicate that this effect is attributed to the dynamic coordination of the pyridyl group to silicon in the cation radical intermediate. Such coordination also facilitates the selective C-Si bond cleavage.

DOI： 10.1246/cl.1999.251

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Quantitative analysis of the chiral amplification in the amino alcohol- promoted asymmetric alkylation of aldehydes with dialkylzincs

Masato Kitamura, Seiji Suga, Hiromasa Oka, Ryoji Noyori

Journal of the American Chemical Society 120 ( 38 ) 9800 - 9809 1998年9月

掲載種別：研究論文（学術雑誌）

Asymmetric reaction of dimethylzinc and benzaldehyde in the presence of (2S)-3-exo-(dimethyl-amino)isoborneol [(2S)-DAIB] exhibits unusual nonlinear phenomena. The enantiomeric purity of the product is much higher than that of the chiral source, DAIB, while the rate of the enantioselective catalysis decreases considerably as the enantiomeric excess (ee) of DAIB is lowered. Such effects originate from the reversible homochiral and heterochiral interaction of the coexistent enantiomeric zinc amino alkoxide catalysts which are formed from dimethylzinc and (2S)- and (2R)-DAIB. The thermodynamics of the five-component equilibration between the two monomers and three dimers, when coupled with the kinetics of the alkylation, strongly affects the extent of enantioselectivity and the reaction rate of the alkylation reaction. The overall profile of the nonlinear effects has been clarified mathematically using experimentally available parameters, viz., the equilibrium constants of the dimer/monomer conversion and the association of the monomeric catalyst with the organozinc and aldehyde, the rate constant of alkyl transfer from the catalyst/dimethylzinc/aldehyde mixed complex, the ee of DAIB, and the concentrations of DAIB, dimethylzinc, and aldehyde. 3D graphics are presented for the correlation of the enantiomeric purity of the product with DAIB ee and the concentrations of dimethylzinc and aldehyde and for the relationship between the reaction rate, DAIB ee, and the concentrations of the organozinc and aldehyde. The computer simulation is in good agreement with the experimental results, confirming thai the nonlinear effects result from the competition of two enantiomorphic catalytic cycles involving the monomeric chiral zinc catalysts rather than the diastereomorphic catalytic cycles with dinuclear zinc catalysts. Furthermore, this study indicates that the degree of nonlinear effects in asymmetric catalysis could be affected not only by the catalyst ee but also by various reaction parameters, particularly the concentrations of the catalyst, reagent, and substrate as well as the extent of conversion.

DOI： 10.1021/ja981740z

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Competition between electroauxiliaries. Selective electrochemical oxidation of heteroatom compounds having silicon and tin on the same carbon

Jun Ichi Yoshida, Mitsuru Watanabe, Hideaki Toshioka, Masayuki Imagawa, Seiji Suga

Chemistry Letters ( 10 ) 1011 - 1012 1998年

掲載種別：研究論文（学術雑誌）

The selective electrochemical oxidation of heteroatom compounds having two different types of electroauxiliaries, i.e. silicon and tin on the same α carbon has been achieved. The C-Sn bond was cleaved selectively and a nucleophile was introduced. The second oxidation of the compound thus obtained gave rise to the cleavage of the C-Si bond and the introduction of a second nucleophile. The present study indicates the feasibility of the redox potential based strategies using electroauxiliaries.

DOI： 10.1246/cl.1998.1011

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Homochiral and heterochiral dimers of the methylzinc alkoxide formed from dimethylzinc and enantiomeric 3-exo-(dimethylamino)isoborneol - Origin of the distinct differences in solution-phase behavior and crystal structures

M. Kitamura, M. Yamakawa, H. Oka, S. Suga, R. Noyori

Angewandte Chemie - International Edition in English 35 ( 17 ) 1173 - 1181 1996年

掲載種別：研究論文（学術雑誌）

Dimethylzinc reacts with (2S)or (2 R)-3-exo-(dimethylamino)isoborneol [(2S)- or (2R)-DAIB] to eliminate methane and produce a tricoordinate methylzinc aminoalkoxide, which forms a dimeric structure. The homochiral dimerization of the enantiomeric compound leads to the chiral, (S,S) or (R.R) dinuclear Zn complex, while the heterochiral interaction forms the meso (S,R) dinuclear compound. In both solution anti crystalline state, the heterochiral dimer is more stable than the homochiral dimer. This stability difference in solution is the origin of the chirality amplification observed in the amino alcohol promoted asymmetric addition of dimethylzinc to benxaldehyde. In toluene, the homochiral dimer dissociates more readily into the monomer than the heterochiral isomer and also undergoes dissociation of the N Zn dative bond making the two N-methyl groups equivalent. The differences in solution behavior between the diastereomers can be understood by comparing their crystal structures. X-ray analysis indicates that the labile Zn O and Zn N bonds in the (S,S) dimer are longer than those in the (S,R) isomer. Skeletal congestion caused by the polycyclic framework is the prime factor determining the properties of the dinuclear Zn complexes, with both steric and electronic factors governing their geometries. The distances between the C-2 proton and N-CH3 of the other DAIBmoiety in the homochiral dimer are close to the sum of the van der Waals radii. A significant nuclear Overhauser effect is seen between these protons in the homochiral dimer. The tetrahedral Zn atoms in the dinuclear complexes are linked covalently to the methyl group, to two oxygen atoms through covalent/electrostatic hybrid bonds, and to the dimethylamino group through electrostatic interaction. The repulsive interaction of the 1,3-syn-oriented Zn CH3 bonds significantly contributes to the lower stability of the homochiral dimeric complex. The N Zn interaction in the homochiral dimer is labile, owing to the increase in the electrostatic interaction between the Zn atom and the neighboring oxygen atoms. This view is supported by the ab initio molecular orbital calculations of the model systems.

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Masato Kitamura, Masashi Yamakawa, Hiromasa Oka, Seiji Suga, Ryoji Noyori

Chemistry - A European Journal 2 ( 9 ) 1173 - 1181 1996年

掲載種別：研究論文（学術雑誌）

Dimethylzinc reacts with (2S)-or (2R)-3-exo-(dimethylamino)isoborneol [(2S)- or (2R)-DAIB] to eliminate methane and produce a tricoordinate methylzinc aminoalkoxide, which forms a dimeric structure. The homochiral dimerization of the enantiomeric compound leads to the chiral, (S,S) or (R,R) dinuclear Zn complex, while the heterochiral interaction forms the meso (S,R) dinuclear compound. In both solution and crystalline state, the heterochiral dimer is more stable than the homochiral dimer. This stability difference in solution is the origin of the chirality amplification observed in the amino alcohol promoted asymmetric addition of dimethylzinc to benzaldehyde. In toluene, the homochiral dimer dissociates more readily into the monomer than the heterochiral isomer and also undergoes dissociation of the N-Zn dative bond making the two N-methyl groups equivalent. The differences in solution behavior between the diastereomers can be understood by comparing their crystal structures. X-ray analysis indicates that the labile Zn-O and Zn-N bonds in the (S,S) dimer are longer than those in the (S,R) isomer. Skeletal congestion caused by the polycyclic framework is the prime factor determining the properties of the dinuclear Zn complexes, with both steric and electronic factors governing their geometries. The distances between the C-2 proton and N-CH3 of the other DAIB moiety in the homochiral dimer are close to the sum of the van der Waals radii. A significant nuclear Overhauser effect is seen between these protons in the homochiral dimer. The tetrahedral Zn atoms in the dinuclear complexes are linked covalently to the methyl group, to two oxygen atoms through covalent/electrostatic hybrid bonds, and to the dimethylamino group through electrostatic interaction. The repulsive interaction of the 1,3-synoriented Zn-CH3 bonds significantly contributes to the lower stability of the homochiral dimeric complex. The N-Zn interaction in the homochiral dimer is labile, owing to the increase in the electrostatic interaction between the Zn atom and the neighboring oxygen atoms. This view is supported by the ab initio molecular orbital calculations of the model systems. © VCH Verlagsgesellschaft mbH, 1996.

DOI： 10.1002/chem.19960020921

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Self and Nonself Recognition of Asymmetric Catalysts. Nonlinear Effects in the Amino Alcohol-Promoted Enantioselective Addition of Dialkylzincs to Aldehydes

Masato Kitamura, Seiji Suga, Makoto Niwa, Ryoji Noyori

Journal of the American Chemical Society 117 ( 17 ) 4832 - 4842 1995年5月

掲載種別：研究論文（学術雑誌）

Chiral β-dialkylamino alcohols promote enantioselective alkylation of aldehydes by dialkylzincs, where a tricoordinate alkylzinc aminoalkoxide in equilibrium with its dimer acts as a true catalyst. The presence of other aminoalkoxides causes nonlinear effects on the rate and stereoselectivity of the enantioselective catalysis. This is a general phenomenon where the extent of the departure from the linearity is highly affected by the nature of the amino alcohols. Systematic investigation using (2S)-3-exo-(dimethylamino)isobomeol and its stereoisomers as well as achiral 2-(dimethylamino)-1,1-dimethylethanol has revealed that the self and nonself recognition of the asymmetric catalysts are the major source of this unusual phenomena. The relative significance of these recognitions affects the overall profile of asymmetric catalysis. © 1995, American Chemical Society. All rights reserved.

DOI： 10.1021/ja00122a013

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Enantiomer recognition of asymmetric catalysts. Thermodynamic properties of homochiral and heterochiral dimers of the methylzinc alkoxide formed from dimethylzinc and enantiomeric 3-exo-(dimethylamino)isoborneol

Masato Kitamura, Seiji Suga, Makoto Niwa, Ryoji Noyori, Zong Xi Zhai, Hiroshi Suga

Journal of Physical Chemistry 98 ( 48 ) 12776 - 12781 1994年

掲載種別：研究論文（学術雑誌）

Reaction of dimethylzinc and (2S)- or (2R)-3-exo-(dimethylamino)isoborneol forms methylzinc alkoxide 1, which forms a dimeric structure 2 in a reversible manner. Depending on the chirality of the monomer 1, three stereoisomeric dinuclear complexes are formed; the homochiral dimerization of 1 leads to (S,S)- or (R,R)-2, whereas the heterochiral interaction forms (S,R)-2. The heterochiral dimer is thermodynamically favored over the homochiral dimer in both toluene solution and crystalline states. The vapor pressure osmometry method has revealed that the stereoisomeric dimers 2 in toluene are in equilibrium with the monomer 1 with dissociation constants Khomo = (3.0 ± 1.0) × 10-2 and Khetero ≅ 1 × 10-5 at 40°C, respectively. Calorimetric determination of the enthalpies of solution of the crystalline compounds indicates that the S,R heterochiral dimer is more stable than the S,S or R,R homochiral dimer by 3.4 ± 0.8 kJ mol-1 in the solid state. © 1994 American Chemical Society.

DOI： 10.1021/j100099a048

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Syntheses of dibenzo[c,e][1,2]diselenin and related novel chalcogenide heterocyclic compounds

Shizuaki Murata, Toshiyasu Suzuki, Akira Yanagisawa, Seiji Suga

Journal of Heterocyclic Chemistry 28 ( 2 ) 433 - 438 1991年

掲載種別：研究論文（学術雑誌）

Reaction of 2,2′‐dilithio‐1,1′‐binaphthyl with selenium followed by air oxidation gives a mixture of dinaph‐thoselenophene and dimer and oligomers of 2,2′‐diseleno‐1,1′‐binaphthyl. 2,2′‐Dilithio‐1,1′‐biphenyl reacts with selenium to afford dibenzo[c,e][1,2]diselenin. Structures of the dimeric 2,2′‐diseleno‐1,1′‐binaphthyl and dibenzo[c,e][1,2]diselenin have been confirmed by X‐ray crystallographic analyses. Similar reaction of 2,2′‐dilithio‐1,1′‐binaphthyl with sulfur or tellurium gives a mixture of dinaphthothiophene and dinaphtho[2,1‐c:‐1′,2′‐e][1,2]dithiin or a mixture of dinaphthotellurophene and oligomer of 2,2′‐ditelluro‐1,1′‐binaphthyl, respectively. Dibenzotellurophene and oligomer of 2,2′‐ditelluro‐1,1′‐biphenyl are obtained from reaction of 2,2′‐dilithio‐1,1′‐biphenyl with tellurium. Copyright © 1991 Journal of Heterocyclic Chemistry

DOI： 10.1002/jhet.5570280243

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Enantioselective addition of diorganozincs to aldehydes catalyzed by β-amino alcohols

R. Noyori, S. Suga, K. Kawai, S. Okada, M. Kitamura, N. Oguni, M. Hayashi, T. Kaneko, Y. Matsuda

Journal of Organometallic Chemistry 382 ( 1-2 ) 19 - 37 1990年2月

掲載種別：研究論文（学術雑誌）

Nucleophilic addition of dialkylzincs to aldehydes in hydrocarbon solvents is markedly accelerated by the presence of a catalytic amount of a β-dialkylamino alcohol. Use of certain sterically constrained chiral amino alcohols such as 3-exo-(dimethylamino)isoborneol or 1-t-butyl-2-piperidinoethanol effects highly enantioselective catalysis giving secondary alcohols in up to 99% ee. Dimethyl-, diethyl-, di-n-butyl-, and di-n-pentyl-zincs have been employed for the alkylation of substituted benzaldehydes and some olefinic or aliphatic aldehydes. Configurational correlation between the chiral auxiliary and alkylation products is discussed. © 1990.

DOI： 10.1016/0022-328X(90)85212-H

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Enantioselective Addition of Dialkylzincs to Aldehydes Promoted by Chiral Amino Alcohols. Mechanism and Nonlinear Effect

M. Kitamura, S. Okada, S. Suga, R. Noyori

Journal of the American Chemical Society 111 ( 11 ) 4028 - 4036 1989年5月

掲載種別：研究論文（学術雑誌）

In the presence of a catalytic amount of (-)-3-exo-(dimethylamino)isoborneol (DAIB), reaction of dialkylzincs and aldehydes is accelerated markedly to give, after hydrolysis, the corresponding S-alcohols in high enantiomeric purity. The reaction mechanism and origin of the enantioselection have been elucidated on the basis of the kinetic measurement, alkylscrambling experiments, single-crystal X-ray analysis, 1H NMR study, molecular weight determination of certain key intermediates. Reaction of DAIB and dimethylzinc in a 1:1 molar ratio produces a single dinuclear zinc chelate complex, which does not alkylate benzaldehyde but acts as catalyst precursor. The alkylation proceeds via a dinuclear zinc species containing the DAIB auxiliary, an aldehyde ligand, and three alkyl groups, where it is the bridging alkyl group, rather than the terminal alkyls, that migrates from zinc to the aldehyde carbon. Kinetic measurements and temperature effects on the enantioselectivity indicate that the alkyl transfer process is the turnover-limiting and stereodetermining step. A new type of nonlinear effect has been observed in this enantioselective alkylation. For example, reaction of benzaldehyde and diethylzinc in the presence of 8 mol % of (-)-DAIB in 15% ee leads to (S)-1-phenyl-1-propanol in 95% ee. This unusual phenomenon is a result of a marked difference in chemical properties of the diasteromeric dinuclear complexes formed from dialkylzincs and the DAIB auxiliary. Reaction of equimolar amounts of dimethylzinc and enantiomerically pure DAIB affords a dinuclear chelate complex with C2 chirality, which acts as the active catalyst precursor of the alkylation. By contrast, dimethylzinc and racemic DAIB generate a more stable, but much less reactive, dinuclear complex possessing a meso, C1 structure, rather than a racemic mixture of the chiral complex. © 1989, American Chemical Society. All rights reserved.

DOI： 10.1021/ja00193a040

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Enantioselective alkylation of carbonyl compounds. From stoichiometric to catalytic asymmetric induction

R. Noyori, S. Suga, K. Kawai, S. Okada, M. Kitamura

Pure and Applied Chemistry 60 ( 11 ) 1597 - 1606 1988年1月

掲載種別：研究論文（学術雑誌）

Multinuclear organometallic species play a significant role in alkylation of carbonyl compounds. Enantioselective alkylation of aldehydes using a 1:1 reagent/substrate stoichiometry is achievable by chirally modified lithium/magnesium binary organometallic reagents. For example, diethylmagnesium treated with di-O-lithio-(S)-2,2' ‘-dihydroxy-1,1’-binaphthyl reacts with benzaldehyde in a THF—dimethoxyethane mixture at-100 °C to give (S)-1-phenyl-1-propanol in 92% ee. In the presence of a catalytic quantity of (-)-3-exo-(dimethylamino)isoborneol (DAIB), reaction of dialkylzincs and aldehydes in nonpolar media is accelerated greatly to lead to the corresponding S alcohols in very high enantiomeric excesses (up to 99% ee). The enantioselective catalysis involves fluxional organozinc species and the product-forming dinuclear intermediate possesses DAIB auxiliary, an aldehyde ligand, and three alkyl groups, where it is the bridging alkyl group, rather than the terminal alkyls, that migrates from zinc to the carbonyl carbon. © 1988 IUPAC

DOI： 10.1351/pac198860111597

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Catalytic Asymmetric Induction. Highly Enantioselective Addition of Dialkylzincs to Aldehydes

M. Kitamura, S. Suga, K. Kawai, R. Noyori

Journal of the American Chemical Society 108 ( 19 ) 6071 - 6072 1986年

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