Publications by authors named "Hidekazu Arii"

14 Publications

  • Page 1 of 1

Intramolecular Chain Hydrosilylation of Alkynylphenylsilanes Using a Silyl Cation as a Chain Carrier.

Molecules 2016 Aug 1;21(8). Epub 2016 Aug 1.

Graduate School of Science and Technology, Gunma University, 1-5-1 Tenjin-cho, Kiryu, 376-8515 Gunma, Japan.

Diorganyl[2-(trimethylsilylethynyl)phenyl]silanes 1a-c and methyl-substituted phenylsilanes 1d and 1e were treated with a small amount of trityl tetrakis(pentafluorophenyl)borate (TPFPB) as an initiator in benzene to afford the corresponding benzosiloles (2a-e) in moderate to good yields. However, no reaction was observed for the reaction using [2-(1-hexynyl)phenyl]diisopropylsilane lf. The methyl substituent was tolerated under the reaction conditions and increased the yield of the corresponding benzosilole depending on the substitution position. From the result using 1f, the current reaction was found to require the trimethylsilyl group, which can stabilize intermediary alkenyl carbocations by the β-silyl effect. The current reaction can be considered an intramolecular chain hydrosilylation of alkynylarylsilanes involving silyl cations as chain carriers. Therefore, the silyl cations generated by hydride abstraction from hydrosilanes 1 with the trityl cation causes intramolecular electrophilic addition to the C-C triple bond to form ethenyl cations, which abstract a hydride from 1 to afford benzosiloles 2 with the regeneration of the silyl cations.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/molecules21080999DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6273890PMC
August 2016

Regioselective and Stereospecific Dehydrogenative Annulation Utilizing Silylium Ion-Activated Alkenes.

J Org Chem 2016 08 12;81(15):6314-9. Epub 2016 Jul 12.

Graduate School of Science and Technology, Gunma University , 1-5-1 Tenjin-cho, Kiryu, 376-8515 Gunma, Japan.

Treatment of dialkylbenzylsilanes (1) with trityl tetrakis(pentafluorophenyl)borate (TPFPB) afforded the corresponding silylium ions in equilibrium with their intra- or intermolecular π-complexes, which underwent dehydrogenative annulation with various alkenes to form 1,2,3,4-tetrahydro-2-silanaphthalenes (4) in up to 82% isolated yield. Sterically bulkier substituents on the silicon atom tended to increase the yield of cyclic products 4. The annulation products retained the stereochemistry in cases of the reactions using internal alkenes. The use of diisopropyl(1-naphthyl)silane (2) instead of 1 also resulted in annulation to obtain the 2,3-dihydro-1-sila-1H-phenalene derivatives 6. Electrophilic aromatic substitution at the 8-position was predominant, despite the two potentially reactive positions on the naphthyl group. The steric hindrance of the naphthyl group prevented addition of the cis-alkene to the silylium ion, which would considerably decrease yields of the desired products from 2 compared to those from 1.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.joc.6b00793DOI Listing
August 2016

Silylium ion-promoted dehydrogenative cyclization: synthesis of silicon-containing compounds derived from alkynes.

Chem Commun (Camb) 2014 Jun;50(50):6649-52

Department of Chemistry, Gakushuin University, 1-5-1 Mejiro, Toshima-ku, 171-8588 Tokyo, Japan.

Treatment of dialkylbenzylsilane (1) with trityl tetrakis(pentafluorophenyl)borate (TPFPB) in the presence of terminal or internal alkynes (3) and 2,6-di-tert-butyl-4-methylpyridine gave the corresponding 1,2-dihydro-2-silanaphthalene derivatives (4) in 34-82% yields.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1039/c4cc01648cDOI Listing
June 2014

Coordination of a chiral tin(II) cation bearing a bis(oxazoline) ligand with tetrahydrofuran derivatives.

Dalton Trans 2012 Aug;41(36):11195-200

Department of Chemistry, Gakushuin University, Tokyo, Japan.

The reaction of SnCl(2) with the lithio derivative of a bis(oxazoline) ligand precursor afforded the enantiomeric chlorostannylene whose chloride ion can be substituted by several neutral or anionic Lewis donors. Abstraction of the chloride ion from the chlorostannylene with silver salts gave the corresponding tetrahydrofuran (THF) complexes of a chiral tin(ii) cation in 1,2-dimethoxyethane (DME) containing THF. That is, the reaction with silver hexafluoroantimonate (AgSbF(6)) afforded the THF complex without interaction with the counteranion. In contrast, reaction with silver triflate (AgOTf) gave the THF complex whose tin center had a pseudo-trigonal bipyramidal structure with two nitrogen atoms of a bidentate ligand and a lone pair at the equatorial positions and one of the oxygen atoms of triflate and an oxygen atom of THF at the apical positions in the solid state. Use of 3-methyltetrahydrofuran (3-MeTHF) instead of THF afforded the 3-MeTHF complexes, where the R-enantiomer of 3-MeTHF predominantly coordinates to the tin center. The previously reported germanium(II) analogue of the tin(II) cation indicated a similar enantioselectivity for the coordination of 3-MeTHF on the germanium center.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1039/c2dt31187aDOI Listing
August 2012

Low-coordinate germanium(II) centers within distorted axially chiral seven-membered chelates: stereo- and enantioselective cycloadditions.

Angew Chem Int Ed Engl 2012 Jul 5;51(27):6738-41. Epub 2012 Jun 5.

Department of Chemistry, Gakushuin University, 1-5-1 Mejiro, Toshima-ku, 171-8588 Tokyo, Japan.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/anie.201201566DOI Listing
July 2012

m-Carborane-based chiral NBN pincer-metal complexes: synthesis, structure, and application in asymmetric catalysis.

Inorg Chem 2011 May 25;50(9):4149-61. Epub 2011 Mar 25.

Department of Chemistry, Faculty of Science, Gakushuin University, 1-5-1 Mejiro, Tokyo 171-8588, Japan.

We have succeeded in synthesizing m-carborane-based chiral NBN-pincer ligands, 1,7-bis(oxazolinyl)-1,7-dicarba-closo-dodecaborane (Carbox) (7-9). The combination of bis(hydroxyamides) and 3 equiv of diethylaminosulfur trifluoride (DAST) is a key step for cyclization to form oxazoline rings in excellent yields. X-ray crystal structures of these ligands confirmed three donor sites, one central B and two flanking N atoms in fixed positions. The electrophilic halogenation of the Carbox pincer ligands with iodine and a catalytic amount of Lewis acid led to ring-opening of the oxazolines and afforded bis(haloamides) (13 and 14). The air- and moisture-stable Carbox pincer complexes of rhodium(III), nickel(II), and palladium(II) were synthesized by the oxidative addition of RhCl(3)·3H(2)O, Ni(COD)(2), and Pd(CH(3)CN)(4)[BF(4)](2) to the Carbox pincer ligands (7-9), respectively. The catalytic activity of the rhodium(III) complexes (18-20) was examined for the asymmetric conjugate reduction of α,β-unsaturated esters and reductive aldol reaction. Among these catalysts, [(S,S)-Carbox-iPr]Rh(OAc)(2)·H(2)O (18) showed the highest enantioselective catalytic ability for both asymmetric conjugate reduction and reductive aldol reaction.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/ic2002095DOI Listing
May 2011

Syntheses of mono- and dinuclear silylplatinum complexes bearing a diphosphino ligand via stepwise bond activation of unsymmetric disilanes.

Dalton Trans 2010 Jul 7;39(28):6434-40. Epub 2010 Jun 7.

Department of Chemistry, Gakushuin University, 1-5-1 Mejiro, Toshima-ku, Tokyo 171-8588, Japan.

Zero-valence platinum complex [Pt(dppe)(eta(2)-C(2)H(4))] (1, dppe = 1,2-bis(diphenylphosphino)ethane) treated with disilanes HR(1)R(2)SiSiMe(3) (a, R(1) = R(2) = Me; b, R(1) = R(2) = Ph; c, R(1) = H, R(2) = Ph) afforded the corresponding disilanylplatinum hydrides [Pt(dppe)(H)(SiR(1)R(2)SiMe(3))] (2a-c) by oxidative addition of the Si-H bond to the platinum center. The 1,2-silyl migration in 2a,b led to the formation of bis(silyl)platinum complexes [Pt(dppe)(SiHR(1)R(2))(SiMe(3))] (3a,b) with a first-order rate constant of 7.2(2) x 10(-4) s(-1) at 25 degrees C for 2a and 3.86(4) x 10(-4) s(-1) at 40 degrees C for 2b, whereas 2c with R(1) = H followed by the transient generation of 3c dimerized rapidly to give the bis(mu-silylene)diplatinum complex [Pt(dppe)(mu-SiHPh)](2) (4c) in a mixture of cis/trans isomers. Heating of the toluene solution of 3b at 100 degrees C resulted in a similar dimerization to 4b. In addition, a trinuclear platinum complex [Pt(3)(dppe)(3)(mu(3)-SiPh)(2)] (5) with a trigonal bipyramidal Pt(3)Si(2) core arose from the reaction of 4c with 1 at 60 degrees C in toluene. Unsymmetric disilanes therefore accomplished the syntheses of various monomeric and dimeric platinum complexes via 1,2-hydrogen and silyl migration to the platinum center.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1039/c000545bDOI Listing
July 2010

Formation of a bridged butterfly-type mu-eta2:eta2-peroxo dicopper core structure with a carboxylate group.

J Am Chem Soc 2008 Dec;130(49):16444-5

Department of Applied Chemistry, Faculty of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/ja804201zDOI Listing
December 2008

Self-assembled monolayer electrode of a diiron complex with a phenoxo-based dinucleating ligand: observation of molecular oxygen adsorptionldesorption in aqueous media.

Chem Commun (Camb) 2008 Jan(3):392-4

Department of Applied Chemistry, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya, 466-8555, Japan.

The phenoxo-based dinucleating ligand, 2,6-bis[bis(6-pivalamido-2-pyridylmethyl)amino-methyl-4-aminophenol (1), and its Fe2(II) complex, [Fe2(II)(1)(PhCOO)2](CF3SO3) (2), were prepared and 2 deposited on the Au surface (2/Au) is much more stable than in solution and exhibits redox behavior in aqueous media as well as reversible adsorption/desorption of oxygen at room temperature.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1039/b711802cDOI Listing
January 2008

Design of Salen-type Ni(II) complexes for recognition of DNA base sequence.

Nucleic Acids Symp Ser (Oxf) 2007 (51):189-90

Department of Applied Chemistry, Faculty of Science and Engineering, Chuo University, 1-13-27, Kasuga, Bunkyo, Tokyo 112-8551, Japan.

The DNA binding properties of cationic salen-type Ni(II) complexes (Fig. 1) have been studied by CD and NMR measurements. The binding constants estimated for poly(dA-dT)2 and poly(dA)poly(dT) revealed that (1) binds more preferentially to poly(dA)poly(dT) than to poly(dA-dT)2, and vice versa for (2). The intermolecular NOE and chemical shift change of the oligonucleotides, d(CGCGAATTCGCG)2 (ODN1) and d(CGCGTATACGCG)2 (ODN2) indicated that the two complexes bound to the minor grooves at AT-rich site of the ODNs from the "en" bridging side. The difference in the sequence specificity between (1) and (2) was attributed to the difference in the width of the minor groove; (2) recognized the wider minor groove of ODN2 'TATA' region. In contrast to (1) and (2), the asymmetric complex (3) bound to the major groove at terminal GC-rich site of ODN1. In this study, we could reveal that hydrophobic interaction is an important factor for base sequence recognition and an appropriate modification of the salen could switch the binding site from minor to major groove of DNA.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/nass/nrm095DOI Listing
April 2008

Co(III) complexes with N2(SO)2-type equatorial planar ligands similar to the active center of nitrile hydratase: role of the sulfenate group in the enzymatic reaction.

Inorg Chem 2007 Nov 24;46(24):10345-53. Epub 2007 Oct 24.

Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan.

In order to gain an understanding of the role of the sulfenyl group of nitrile hydratase (NHase), a new Co(III) complex with a sulfenyl-type ligand (LC=O:N2(SO)2), Na[CoIII(LC=O:N2(SO)2)(tBuNC)2] (2), was synthesized. The compound includes two amide groups, two sulfenate sulfurs in the equatorial plane, and two tBuNC molecules in the axial positions. Characterization of the compound was performed by UV-vis spectroscopic, IR spectral, thermogravimetric (TG), and X-ray structure analytical methods. The results are discussed in the context of Co(III) complexes containing the corresponding sulfur-type (LC=O:N2S2) (1) and sulfinyl-type ligands (LC=O:N2(SO2)2) (3). Complex 2 crystallized with the formula Na[CoIII(LC=O:N2(SO)2)(tBuNC)2].urea.2H2O.0.5EtOH. The X-ray structure revealed that the Co(III) complex has an octahedral geometry with Co-S=av. 2.221 A, Co-N=av. 1.998 A, and Co-C=av. 1.87 A. The sulfenyl oxygen and amidate carbonyl oxygen are linked to urea, water, EtOH, and Na+ and participate in a hydrogen-bond and an electrostatic interaction. IR and TG measurements demonstrated that the coordination strength of tBuNC to the Co atom increases as follows: 1<2<3. Complex 2 has almost the same stability as 3 in all solutions tested, although 1 exhibits a release of axial ligands in nonaqueous solutions. DFT calculations for 1, 2, and 3 demonstrated that Milliken atomic charges of the Co(III) centers are +1.466, +1.536, and +1.542, respectively, indicating that the extent of oxidation of the sulfur atoms increases the Lewis acidity of the Co(III) centers. Interestingly, the solution-state IR spectrum of 2 exhibits a solvent-dependent S-O stretching frequency. The frequency decreases with an increase in the electrophilicity (acceptor number) of the solvent. This solvent dependence was not observed for 3, which has a sulfinate (SO2) group, suggesting that the sulfenyl oxygen atom has nucleophilic character and promotes strong binding of the tBuNC molecule to lower the reaction barrier. These findings may suggest that the sulfenate oxygen in native NHase acts as a base (proton acceptor) and contributes to the activation of a water molecule and/or nitrile molecule.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/ic701107xDOI Listing
November 2007

Syntheses, characterization, and dioxygen reactivities of Cu(I) complexes with cis,cis-1,3,5-triaminocyclohexane derivatives: a Cu(III)2O2 intermediate exhibiting higher C-H activation.

Inorg Chem 2007 Apr 20;46(8):3322-35. Epub 2007 Mar 20.

Graduate School of Engineering, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan.

Six Cu(I) complexes with cis,cis-1,3,5-triaminocyclohexane derivatives (R3CY, R = Et, iBu, and Bn), [Cu(MeCN)(Et3CY)]SbF6 (1), [Cu(MeCN)(iBu3CY)]SbF6 (2), [Cu(MeCN)(Bn3CY)]SbF6 (3), [Cu(CO)(Et3CY)]SbF6 (4), [Cu(CO)(iBu3CY)]SbF6 (5), and [Cu(CO)(Bn3CY)]SbF6 (6), were prepared to probe the ability of copper complexes to effectively catalyze oxygenation reactions. The complexes were characterized by elemental analysis, electrochemical and X-ray structure analyses, electronic absorption spectroscopy, IR spectroscopy, 1H NMR spectroscopy, and ESI mass spectrometry. The crystal structures of 1-3 and 6 and the CO stretching vibrations (nuCO) of 4-6 demonstrate that the ability of R3CY to donate electron density to the Cu(I) atom is stronger than that of the previously reported ligands, 1,4,7-triazacyclononane (R3TACN) and 1,4,7-triazacyclodecane (R3TACD). Reactions of complexes 1-3 with dioxygen in THF or CH2Cl2 at -105 to -80 degrees C yield bis(mu-oxo)dicopper(III) complexes 7-9 as intermediates as confirmed by electronic absorption spectroscopy and resonance Raman spectroscopy. The Cu-O stretching vibrations, nu(Cu-O) for 7 (16O2: 553, 581 cm-1and 18O2: 547 cm-1) and 8 (16O2: 571 cm-1 and 18O2: 544 cm-1), are observed in a lower energy region than previously reported for bis(micro-oxo) complexes. The decomposition rates of complexes 7-9 in THF at -90 degrees C are 2.78 x 10-4 for 7, 8.04 x 10-4 for 8, and 3.80 x 10-4 s-1 for 9. The decomposition rates of 7 and 8 in CH2Cl2 were 5.62 x 10-4 and 1.62 x 10-3 s-1, respectively, and the thermal stabilities of 7-9 in CH2Cl2 are lower than the values measured for the complexes in THF. The decomposition reactions obeyed first-order kinetics, and the H/D isotope experiments for 8 and 9 indicate that the N-dealkylation reaction is the rate-determining step in the decomposition processes. On the other hand, the decomposition reaction of 7 in THF results in the oxidation of THF (acting as an exogenous substrate) to give 2-hydroxy tetrahydrofuran and gamma-butyrolactone as oxidation products. Detailed investigation of the N-dealkylation reaction for 8 by kinetic experiments using N-H/D at -90 degrees C showed a kinetic isotope effect of 1.25, indicating that a weak electrostatic interaction between the N-H hydrogen and mu-oxo oxygen contributes to the major effect on the rate-determining step of N-dealkylation. X-ray crystal structures of the bis(micro-hydroxo)dicopper(II) complexes, [Cu2(OH)2(Et3CY)2](CF3SO3)2 (10), [Cu2(OH)2(iBu3CY)2](CF3SO3)2 (11), and [Cu2(OH)2(Bn3CY)2](ClO4)2 (12), which have independently been prepared as the final products of bis(micro-oxo)dicopper(III) intermediates, suggest that an effective interaction between N-H and mu-oxo in the Cu(III)2(micro-O)2 core may enhance the oxidation ability of the metal-oxo species.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/ic062206sDOI Listing
April 2007

Copper(II) complexes of 1,10-phenanthroline-derived ligands: studies on DNA binding properties and nuclease activity.

J Inorg Biochem 2005 May;99(5):1205-19

Department of Applied Chemistry, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551, Japan.

A series of copper(II) complexes of the type [Cu(L)]2+, where L = N,N'-dialkyl-1,10-phenanthroline-2,9-dimethanamine and R = methyl (L1), n-propyl (L2), isopropyl (L3), sec-butyl (L4), or tert-butyl (L5) group, have been synthesized. The interaction of the complexes with DNA has been studied by DNA fiber electron paramagnetic resonance (EPR) spectroscopy, emission, viscosity and electrochemical measurements and agarose gel electrophoresis. In the X-ray crystal structure of [Cu(HL2)Cl2]NO3, copper(II) is coordinated to two ring nitrogens and one of the two secondary amine nitrogens of the side chains and two chloride ions as well and the coordination geometry is best described as trigonal bipyramidal distorted square based pyramidal (TBDSBP). Electronic and EPR spectral studies reveal that all the complexes in aqueous solution around pH 7 possess CuN3O2 rather than CuN4O chromophore with one of the alkylamino side chain not involved in coordination. The structures of the complexes in aqueous solution around pH 7 change from distorted tetragonal to trigonal bipyramidal as the size of the alkyl group is increased. The observed changes in the physicochemical features of the complexes on binding to DNA suggest that the complexes, except [Cu(L5)]2+, bind to DNA with partial intercalation of the derivatised phen ring in between the DNA base pairs. Electrochemical studies reveal that the complexes prefer to bind to DNA in Cu(II) rather than Cu(I) oxidation state. Interestingly, [Cu(L5)]2+ shows the highest DNA cleavage activity among all the present copper(II) complexes suggesting that the bulky N-tert-butyl group plays an important role in modifying the coordination environment around the copper(II) center, the Cu(II)/Cu(I) redox potential and hence the formation of activated oxidant responsible for the cleavage. These results were compared with those for bis(1,10-phenanthroline)copper(II), [Cu(phen)2]2+.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jinorgbio.2005.02.020DOI Listing
May 2005

Effect of a conjugated acridine moiety on the binding and reactivity of Cu(II)[9-acridinylmethyl-1,4,7-triazacyclononane] with DNA.

J Inorg Biochem 2004 Nov;98(11):1778-86

Department of Applied Chemistry, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, 112-8551 Tokyo, Japan.

The DNA binding orientation and dynamic behavior of Cu(II) complexes of 1,4,7-triazacyclononane ([9]aneN(3)), 1, and an acridine conjugate, 2, were investigated by DNA fiber EPR (EPR=electron paramagnetic resonance) spectroscopy. Crystal and molecular structure of 2 were determined by X-ray diffraction. It has been shown that 1 binds to DNA in two different modes at room temperature; one species is rapidly rotating and the other is immobilized randomly on the DNA. The introduction of acridine to [9]aneN(3) fixed the [Cu([9]aneN(3))](2+) moiety of 2 in two different environments on the DNA: the g(mid R:mid R:) axis of one species (g( parallel)=2.26) is aligned perpendicularly to the DNA fiber axis whereas that of the other (g( parallel)=2.24) aligns<90 degrees with the DNA fiber axis. The different DNA binding structures of 1 and 2 are reflected also in their different efficiencies of DNA cleavage; 2 was found to be more effective both in oxidative and hydrolytic cleavage reactions.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jinorgbio.2004.07.014DOI Listing
November 2004