研究者詳細 - 依馬　正

論文 - 依馬　正

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Significant effect of acyl groups on enantioselectivity in lipase-catalyzed transesterifications

Tadashi Ema, Soichi Maeno, Yusuke Takaya, Takashi Sakai, Masanori Utaka

Tetrahedron Asymmetry 7 ( 3 ) 625 - 628 1996年3月

掲載種別：研究論文（学術雑誌）

The effect of the acyl group of acylating agents on the enantioselectivity in the lipase-catalyzed transesterification of racemic 2-[(N,N-dimethylcarbamoyl)methyl]-3-cyclopenten-1-ol in diisopropyl ether was found to be significant. The enantioselectivity was enhanced markedly by changing the acylating agent from vinyl acetate to vinyl butyrate, and dropped substantially with longer acyl donors. Other acyl donors were also examined.

DOI： 10.1016/0957-4166(96)00049-3

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Highly efficient and convenient regeneration of NADPH for asymmetric reduction using bakers' yeast cell free extract

Masanori Utaka, Tomoko Yano, Ema Tadashi, Takashi Sakai

Chemistry Letters ( 12 ) 1079 - 1080 1996年

Unusual picosecond ¹(π, π^*) deactivation of ruffled nonplanar porphyrins

Steve Gentemann, Craig J. Medforth, Tadashi Ema, Nora Y. Nelson, Kevin M. Smith, Jack Fajer, Dewey Holten

Chemical Physics Letters 245 ( 4-5 ) 441 - 447 1995年11月

掲載種別：研究論文（学術雑誌）

Time-resolved and steady-state optical data are presented for metal-free meso-tetraalkylporphyrins, H2T(alkyl)P. Introduction of bulky tertiary-butyl or adamantyl substituents at the meso positions induces large ruffling distortions of the macrocycle skeleton that give rise to highly novel photophysical properties of the porphyrins. These include ultrashort 1(π, π*) lifetimes of 10-50 ps at 296 K that, intriguingly, lenghten to 10-15 ns at 78 K, the typical timescale found at both temperatures for planar derivatives such as tetra(n-pentyl) and tetraphenyl porphyrins. The ability of the nonplanar ruffled porphyrins to undergo additional structural deformations in the excited singlet state likely underlies their dramatically enhanced rates of internal conversion. © 1995.

DOI： 10.1016/0009-2614(95)01030-D

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Molecular recognition: New chiral metalloporphyrins as receptor models

Hisanobu Ogoshi, Tadashi Ema, Yusuke Kato, Tadashi Mizutani, Yasuhisa Kuroda

Supramolecular Chemistry 6 ( 1-2 ) 115 - 124 1995年10月

掲載種別：研究論文（学術雑誌）

New chiral metalloporphyrins capable of multi-point recognition are prepared and their recognition behavior, especially chiral recognition, is studied. The first part of the paper is concerned with general formalism for multi-point recognition, where uniqueness of multi-point recognition, isolation of interaction in terms of free energy, enthalpy and entropy, and the meaning of these thermodynamic parameters are discussed. Enantioselective binding of amino acid esters to two new chiral porphyrins is investigated by UV-vis, NMR and IR spectroscopic methods. Chiral recognition is achieved by combination of three recognition interactions between host and guest. © 1995, Taylor & Francis Group, LLC. All rights reserved.

DOI： 10.1080/10610279508032527

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Synthesis and CD spectrum of chiral porphyrin dimer

Tadashi Ema, Shuichi Nemugaki, Sadao Tsuboi, Masanori Utaka

Tetrahedron Letters 36 ( 33 ) 5905 - 5908 1995年8月

Restricted internal rotation of amino acid esters. Quantitative evaluation of rigidity of a molecule in terms of internal rotation entropy

Tadashi Mizutani, Tadashi Ema, Hisanobu Ogoshi

Tetrahedron 51 ( 2 ) 473 - 484 1995年1月

掲載種別：研究論文（学術雑誌）

As a model of molecular recognition of a flexible guest through multi-point recognition, the two-point fixation of the NH2 group and the C=O group of amino acid esters to porphyrin host was investigated from thermodynamic point of view. The negative entropy change owing to restriction of internal rotation around the Cα-C(carbonyl) bond of guest as driven by the two-point fixation was calculated from the following steps: (1) ab initio molecular orbital calculations at the 3-21G level to generate a potential energy surface for internal rotation along the Cα-C(carbonyl) bond and the Cα-Cβ bond, and (2) a calculation of partition function of the system based on classical statistical mechanics. The entropy loss due to the restriction of a rotation around the Cα-C(carbonyl) bond was 5.0 cal·K-1·mol-1 for alanine methyl ester and 1.9 cal·K-1·mol-1 for valine methyl ester, indicating that valine methyl ester is more rigid with respect to the Cα-C(carbonyl) rotation. This entropy loss was found to originate from the correlated rotation of the Cα-C(carbonyl) bond and the Cα-Cβ bond. © 1994.

DOI： 10.1016/0040-4020(94)00909-E

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Crystal structure of a remarkably ruffled nonplanar porphyrin (pyridine)[5,10,15,20-tetra(tert-butyl)porphyrinato]zinc(II)

Mathias O. Senge, Tadashi Ema, Kevin M. Smith

Journal of the Chemical Society, Chemical Communications ( 7 ) 733 - 734 1995年

Ruffling in a Series of Nickel(II) meso-Tetrasubstituted Porphyrins as a Model for the Conserved Ruffling of the Heme of Cytochromes c

W. Jentzen, M. C. Simpson, J. D. Hobbs, X. Song, J. A. Shelnutt, T. Ema, N. Y. Nelson, C. J. Medforth, K. M. Smith, M. Veyrat, M. Mazzanti, R. Ramasseul, J. C. Marchon, T. Takeuchi, W. A. Goddard

Journal of the American Chemical Society 117 ( 45 ) 11085 - 11097 1995年

掲載種別：研究論文（学術雑誌）

Metalloporphyrins undergo remarkable nonplanar distortions of the macrocycle that perturb the chemical and photochemical properties of these important protein cofactors. Further, the tertiary structure of the surrounding protein can manipulate these distortions as a means of regulating biological function. For cytochromes c, for example, an energetically unfavorable, conserved nonplanar distortion of the heme exists and likely plays a role in its electrontransfer function. The heme distortion is primarily of the ruffling (ruf) type (corresponding to the lowest frequency B1u-symmetry normal mode) in which the pyrroles are twisted about the metal–Npyrrole bond. This B1u-symmetry nonplanar distortion is commonly observed in metalloporphyrin crystal structures, as are the saddling (sad) B2u-symmetry distortion, waving (wav) Eg-symmetry distortions, and doming (dom) A2u-symmetry distortion. Each of these nonplanar distortions is expected to result in unique alterations of the chemical and physical properties of the nominally planar porphyrin macrocycle. Symmetrical porphyrin substitution with tetrahedrally bonded atoms at the four meso bridging carbons generally results in the B1u ruffling distortion; therefore, we investigated a series of meso-tetrasubstituted porphyrins for which the substituents vary in size (methyl, ethyl, propyl, pentyl, isopropyl, cyclopropyl derivative 11a, cyclohexyl, apopinenyl (10), tert-butyl, adamantyl), increasing the steric crowding at the periphery. Molecular mechanics calculations show increasing degree of ruffling (CαNNCα angle for opposite pyrroles varies from 0 to 57°) for this series of porphyrins, generally agreeing with the X-ray structures that are available. In addition, the frequencies of the structure-sensitive Raman lines decrease nonlinearly with increasing ruffling angle. The localization of the B1u nonplanar distortion in only the Cα-Cm bond torsion (not the case for the B2u sad distortion) suggests a means by which the B1u distortion might be distinguished from other types of nonplanar distortion by using resonance Raman spectroscopy. Also, the size of the red shifts in the π → π* absorption bands depends on Cα–Cm torsion angle in a nonlinear fashion and the shift is accurately predicted by INDO/s molecular orbital calculations when the nonplanar structures obtained from molecular mechanics are used. © 1995, American Chemical Society. All rights reserved.

DOI： 10.1021/ja00150a008

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Complexation-induced Catalysis in Zinc Insertion into Cationic Porphyrin 査読

Mizutani, T, Koyama, H, Ema, T, Nomura, A, Yoshida, T, Ogoshi, H

Chem. Lett. ( 10 ) 941 - 942 1995年

5,10,15,20‐Tetra‐tert‐butylporphyrin and Its Remarkable Reactivity in the 5‐ and 15‐Positions

Tadashi Ema, Mathias O. Senge, Nora Y. Nelson, Hisanobu Ogoshi, Kevin M. Smith

Angewandte Chemie International Edition in English 33 ( 18 ) 1879 - 1881 1994年9月

掲載種別：研究論文（学術雑誌）

Owing to the steric bulk of the tert‐butyl groups, the reactivity of the novel porphyrin 1, which has a nonplanar macrocyclic framework, deviates distinctly from that of any other known porphyrin. For example, prolonged treatment of 1 in HClO4/MeOH leads to formation of 5,15‐dihydroporphyrin (“porphodi‐methene”) 2. (Figure Presented.) Copyright © 1994 by VCH Verlagsgesellschaft mbH, Germany

DOI： 10.1002/anie.199418791

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Mechanism of Induced Circular Dichroism of Amino Acid Ester-Porphyrin Supramolecular Systems. Implications to the Origin of the Circular Dichroism of Hemoprotein

Tadashi Mizutani, Tadashi Ema, Takashi Yoshida, Thomas Renné, Hisanobu Ogoshi

Inorganic Chemistry 33 ( 16 ) 3558 - 3566 1994年8月

掲載種別：研究論文（学術雑誌）

Circular dichroism (CD) spectra of the complexes between metalloporphyrins and chiral amino acid derivatives exhibited either split type induced CD or single peak induced CD in the Soret region depending on the host-guest combination. Systematic studies on the complexation of amino acid derivatives by porphyrin hosts indicate that intermolecular hydrogen bonding to the carbonyl group of the guest is necessary for the split type induced CD to occur. Molecular orbital calculations of the rotational strength of a porphyrin-amino acid ester complex by the MNDO method predict that the ICD of porphyrin-amino acid ester complexes is determined by the relative geometry of the carbonyl group and the porphyrin plane. The relative geometry of the chromophores expected from the X-ray crystallographic analysis of a complex between leucine methyl ester and a similar host then gives split type induced CD, in agreement with experiment. These experimental and theoretical results indicate that the coupling between the magnetic transition dipole moment (mj) and the electric transition dipole moment (μj) of a carbonyl group and the electric transition dipole moment (μi) of the porphyrin Soret band makes an important contribution to the observed induced CD. © 1994, American Chemical Society. All rights reserved.

DOI： 10.1021/ic00094a020

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Design and Synthesis of a Trifunctional Chiral Porphyrin with C<inf>2</inf> Symmetry as a Chiral Recognition Host for Amino Acid Esters

Tadashi Mizutani, Tadashi Ema, Takashi Tomita, Yasuhisa Kuroda, Hisanobu Ogoshi

Journal of the American Chemical Society 116 ( 10 ) 4240 - 4250 1994年5月

掲載種別：研究論文（学術雑誌）

An intrinsic chiral recognition host, (R,R)- or (S,S)-[trans-5,15-bis(2-hydroxyphenyl)-10-{2,6-bis((methoxycarbonyl)methyl)phenyl}-2,3,17,18-tetraethylporphyrinato]zinc(II) (1), was synthesized by the coupling between (3,3',4,4'-tetraethyl-5,5'-bis(α-hydroxy-2-methoxybenzyl)-2,2'-dipyrryl)methane (8) and dimethyl 2-(bis(2-pyrryl)-methyl)-l,3-benzenediacetate (16). This pyrrylmethanol method made it possible to perform the regiospecific coupling between differently functionalized dipyrromethane units. Host 1 was designed to have three recognition elements: metal coordination, hydrogen bond donor, and hydrogen bond acceptor (and/or steric repulsion) groups. These groups are arranged in a convergent fashion, forming a chiral recognition pocket. Host 1 was resolved into two enantiomers, (+)-1 and (-)-1. The binding constants in CHC13 were determined by UV-vis titration. Host (+)-1 was found to show an enantioselectivity of 2.0-2.8 in respect to l- and d-enantiomers of I1e-OMe, Leu-OMe, Leu-OBzl, Val-OMe, Pro-OMe, and Phe-OMe. Host (+)-1 showed an enantioselectivity of 0.47 in respect to l- and d-enantiomers of serine benzyl ester, indicating that the enantioselectivity was reversed. Reference porphyrins 2-4, which lack some of recognition groups, were also synthesized by the pyrrylmethanol method to clarify the roles of the recognition groups of (+)-1 in thermodynamics of the binding processes. Total free energy change upon binding of l- and d-Ile-OMe to host (+)-l (ΔG°total for L, -5.05, and d, -4.46 kcal/mol) was separated into three terms: metal coordination energy (ΔG°Zn)>-4.15 kcal/mol; hydrogen bond energy (ΔΔG°OH),-1.30 kcal/mol; and steric repulsion energy (ΔΔG°LCOOMe or ΔΔG°DcooMe), +0.40 kcal/mol for l- and +0.99 kcal/mol for d-Ile-OMe. The third recognition group (CH2CO2Me) of (+)-l was found to destabilize the complexes due to steric repulsions. In contrast, the CH2CO2Me group was found to stabilize the complex between d-Ser-OBzl and (+)-l, suggesting that hydrogen bonding between the OH group of serine and the C=O group of (+)-l takes place. On the basis of these thermodynamic studies, chiral recognition was found to be achieved by cooperative functions of these three recognition groups. © 1994, American Chemical Society. All rights reserved.

DOI： 10.1021/ja00089a013

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Recognition of α-Amino Acid Esters by Zinc Porphyrin Derivatives via Coordination and Hydrogen Bonding Interactions. Evidence for Two-Point Fixation from Thermodynamic and Induced Circular Dichroism Spectroscopic Studies

Tadashi Mizutani, Tadashi Ema, Takashi Yoshida, Yasuhisa Kuroda, Hisanobu Ogoshi

Inorganic Chemistry 32 ( 10 ) 2072 - 2077 1993年

掲載種別：研究論文（学術雑誌）

Association constants between [trans-5,15-bis(2-hydroxy-1-naphthyl)-2,3,7,8,12,13,17,18-octaethylporphyrinato]-zinc(II) (1) and a series of α-amino acid esters (RCHNH2CO2CH3) were determined in chloroform by use of a UV-vis titration method. Association constants increased in the order Ala-OMe < Gly-OMe < Val-OMe < Leu-OMe, showing a preference for bulky amino acid esters. Contributions from the metal coordination and hydrogen bonding interactions to the total free energy change were estimated by use of reference compounds having no hydrogen bonding site. The free energy change for the binding of Leu-OMe to 1 in chloroform at 15 °C was −5.3 kcal/mol, which was separated into two contributions, (1) the metal coordination interaction ΔGMC = −3.8 kcal/mol and (2) the hydrogen bonding interaction ΔGHB = −1.5 kcal/mol. Circular dichroism (CD) induced in the porphyrin Soret band of 1 by complexation with optically active amino acid esters was of the split type for all the amino acid esters examined, whereas induced CD of a reference host, [trans-5,15-bis(2-methoxy-1-naphthyl)-2,3,7,8,12,13,17,18-octaethylporphyrinato]zinc(II) (2), was reduced in intensity and not of the split type. We found that the fixation of the carbonyl group of the guest by two-point recognition caused marked enhancements in induced CD. We suggest that the induced CD of 1 was caused by the coupling between the magnetic transition dipole moment of the carbonyl group of guest and the electric transition dipole moment of the Soret band of host. © 1993, American Chemical Society. All rights reserved.

DOI： 10.1021/ic00062a032

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Recognition of chirality and residual groups of amino acid esters using new trifunctional chiral porphyrins with C<inf>2</inf> symmetry

Tadashi Mizutani, Tadashi Ema, Takashi Tomita, Yasuhisa Kuroda, Hisanobu Ogoshi

Journal of the Chemical Society, Chemical Communications ( 6 ) 520 - 522 1993年

掲載種別：研究論文（学術雑誌）

An intrinsic chiral recognition host, [trans-5,15-bis(2-hydroxyphenyl)-10- {2,6-bis(methoxycarbonylmethyl)phenyl}-2,3,17,18-tetraethylporphyrinato]zinc(II) 1, is synthesized and found to show an enantioselectivity of ca. 2: 1 for L- and D-amino acid esters having non-polar residues, whereas it shows a reversed enantioselectivity of ca. 1: 2 for L- and D-Ser-OBzl.

DOI： 10.1039/C39930000520

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Synthesis and Photoreaction of 1,2,3,4-Tetra-t-butylnaphthalene: A Highly Crowded Naphthalene Derivative and Its Valenceisomers

Sadao Miki, Tadashi Ema, Rie Shimizu, Hiroshi Nakatsuji, Zen ichi Yoshida

Tetrahedron Letters 33 ( 12 ) 1619 - 1620 1992年3月

掲載種別：研究論文（学術雑誌）

1,2,3,4-Tetra-t-butylnaphthalene (2), a highly crowded naphthalene derivative, has been synthesized. Upon irradiation, 2 underwent photovalence isomerization to afford 1,2,5,6-tetra-t-butyl-3,4-benzo-3-tricyclo[3.1.0.02,6]-hexene (3). The synthesis of 1,4,5,6-tetra-t-butyl-2,3-benzo-2,5-bicyclo[2.2.0]hexadiene (1), which was used for the synthesis of 2, is also described. © 1992.

DOI： 10.1016/S0040-4039(00)91689-7

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Selective syntheses of unsymmetrical meso-arylporphyrins

Tadashi Ema, Yasuhisa Kuroda, Hisanobu Ogoshi

Tetrahedron Letters 32 ( 35 ) 4529 - 4532 1991年

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