Takanori Shibata - Cochemist

DFT Studies on the Mechanism of the Iridium-Catalyzed Formal [4 + 1] Cycloaddition of Biphenylene with Alkenes

Co-reporter:Hideaki Takano, Natsuhiko Sugimura, Kyalo Stephen Kanyiva, and Takanori Shibata

ACS Omega August 2017? Volume 2(Issue 8) pp:5228-5228

Publication Date(Web):August 30, 2017

DOI:10.1021/acsomega.7b00403

Recently, we reported an Ir-catalyzed formal [4 + 1] cycloaddition of biphenylenes with alkenes, which gave 9,9-disubstituted fluorenes in moderate to excellent yields. We proposed a reaction mechanism that involved the intermolecular insertion of alkenes, β-elimination, and intramolecular insertion based on the results of experimental mechanistic studies. Herein, we further support the proposed mechanism by density functional theory calculations and explain why [4 + 1] cycloaddition proceeds rather than conventional [4 + 2] cycloaddition.Topics: Cycloaddition reaction; Elimination reaction; Elimination reaction; Free energy; Molecular structure; Reaction mechanism;

Sulfur-directed carbon–sulfur bond cleavage for Rh-catalyzed regioselective alkynylthiolation of alkynes

Co-reporter:Takanori Shibata;Akihito Mitake;Yosuke Akiyama;Kyalo Stephen Kanyiva

Chemical Communications 2017 vol. 53(Issue 64) pp:9016-9019

Publication Date(Web):2017/08/08

DOI:10.1039/C7CC04997H

Sulfur-directed sp C–S bond cleavage along with a regioselective reaction with alkynes proceeded to give (Z)-enyne sulfides in high to excellent yields. Mechanistic studies were conducted, including characterization of an intermediate. An intramolecular variant realized the construction of a dibenzodithiepin skeleton, which is a seven-membered ring with two sulfur atoms.

Intramolecular C−H Alkenylation of N-Alkynylindoles: Exo and Endo Selective Cyclization According to the Choice of Metal Catalyst

Co-reporter:Takanori Shibata;Takumi Baba;Hideaki Takano;Kyalo Stephen Kanyiva

Advanced Synthesis & Catalysis 2017 Volume 359(Issue 11) pp:1849-1853

Publication Date(Web):2017/06/06

DOI:10.1002/adsc.201700107

AbstractThe intramolecular reaction of 3-acetyl-N-alkynylindoles proceeded via C−H bond cleavage at the C2 position. Iridium and rhodium catalysts selectively promoted 6-exo-dig and 7-endo-dig cyclization, respectively, and N-fused tricyclic compounds were obtained.

Iridium-Catalyzed Formal [4 + 1] Cycloaddition of Biphenylenes with Alkenes Initiated by C–C Bond Cleavage for the Synthesis of 9,9-Disubstituted Fluorenes

Co-reporter:Hideaki Takano, Kyalo Stephen Kanyiva, and Takanori Shibata

Organic Letters 2016 Volume 18(Issue 8) pp:1860-1863

Publication Date(Web):March 31, 2016

DOI:10.1021/acs.orglett.6b00619

An Ir-catalyzed intermolecular reaction of biphenylenes as a C4 unit with various alkenes as a C1 unit gave 9,9-disubstituted fluorenes in moderate to high yields. Preliminary mechanistic studies revealed that this formal [4 + 1] cycloaddition probably proceeds via C–C bond cleavage, alkene insertion, β-hydrogen elimination, intramolecular alkene insertion, and then reductive elimination. An example of enantioselective reaction was also disclosed.

Enantioselective Synthesis of Aminoindan Carboxylic Acid Derivatives by the Catalytic Intramolecular [2+2+2] Cycloaddition of Amino-Acid-Tethered Triynes

Co-reporter:Yu-ki Tahara;Shuhei Obinata;Kyalo Stephen Kanyiva;Attila Mándi;Tohru Taniguchi;Kenji Monde

European Journal of Organic Chemistry 2016 Volume 2016( Issue 7) pp:1405-1413

Publication Date(Web):

DOI:10.1002/ejoc.201501612

Abstract

The enantioselective synthesis of aminoindan carboxylic acid (Aic) derivatives was achieved by Rh-catalyzed intramolecular [2+2+2] cycloaddition of amino-acid-tethered triynes. This reaction, along with recrystallization, gave chiral tethered Aic derivatives with excellent enantiomeric excess. Subsequent hydrolysis of the tethered Aic compounds afforded chiral Aic derivatives, which were further transformed into a free Aic and its dimethyl ester in good yields.

Catalytic and Enantioselective Synthesis of Chiral Multisubstituted Tribenzothiepins by Intermolecular Cycloadditions

Co-reporter:Yu-ki Tahara;Riku Matsubara;Akihito Mitake;Tatsuki Sato;Dr. Kyalo Stephen Kanyiva;Dr. Takanori Shibata

Angewandte Chemie International Edition 2016 Volume 55( Issue 14) pp:4552-4556

Publication Date(Web):

DOI:10.1002/anie.201511876

Abstract

The first catalytic and highly enantioselective synthesis of tribenzothiepin derivatives was achieved. Two types of intermolecular cycloadditions using either diphenyl-sulfide-tethered diynes or 2-phenyl sulfanylbenzene-tethered diynes with a monoalkyne successfully gave chiral multisubstituted tribenzothiepins in good to excellent ee values under mild conditions. The inversion energy of this saddle-shaped molecule was calculated by measurement of the racemization rate of chiral tribenzothiepins using the Eyring kinetic equation under heating conditions. The present protocol could also be used to prepare a chiral tribenzoselenepin.

Pt-Catalyzed Enantioselective Cycloisomerization for the Synthesis of Planar-Chiral Ferrocene Derivatives

Co-reporter:Takanori Shibata, Ninna Uno, Tomoya Sasaki, and Kyalo Stephen Kanyiva

The Journal of Organic Chemistry 2016 Volume 81(Issue 15) pp:6266-6272

Publication Date(Web):June 27, 2016

DOI:10.1021/acs.joc.6b00825

Enantioselective cycloisomerization of 2-ethynyl-1-ferrocenylbenzene derivatives proceeded by using a chiral cationic platinum catalyst at room temperature. The intramolecular reaction gave planar–chiral naphthalene- and anthracene-fused ferrocene derivatives with high to excellent ee.

Strategies for the Total Synthesis of Clavicipitic Acid

Co-reporter:Mamoru Ito;Yu-ki Tahara;Dr. Takanori Shibata

Chemistry - A European Journal 2016 Volume 22( Issue 16) pp:5468-5477

Publication Date(Web):

DOI:10.1002/chem.201505014

Abstract

Clavicipitic acid is an ergot alkaloid, which was isolated from Claviceps strain and Claviceps fusiformis. Its unique tricyclic azepinoindole skeleton has attracted synthetic chemists, and various strategies have been developed for its total synthesis. These strategies can be generally categorized into two types based on the synthetic intermediates, namely, 4-substituted gramine derivatives and 4-substituted tryptophan derivatives. This Minireview summarizes the reported total syntheses from the point of these two key intermediates

Catalytic and Enantioselective Synthesis of Chiral Multisubstituted Tribenzothiepins by Intermolecular Cycloadditions

Co-reporter:Yu-ki Tahara;Riku Matsubara;Akihito Mitake;Tatsuki Sato;Dr. Kyalo Stephen Kanyiva;Dr. Takanori Shibata

Angewandte Chemie 2016 Volume 128( Issue 14) pp:4628-4632

Publication Date(Web):

DOI:10.1002/ange.201511876

Abstract

The first catalytic and highly enantioselective synthesis of tribenzothiepin derivatives was achieved. Two types of intermolecular cycloadditions using either diphenyl-sulfide-tethered diynes or 2-phenyl sulfanylbenzene-tethered diynes with a monoalkyne successfully gave chiral multisubstituted tribenzothiepins in good to excellent ee values under mild conditions. The inversion energy of this saddle-shaped molecule was calculated by measurement of the racemization rate of chiral tribenzothiepins using the Eyring kinetic equation under heating conditions. The present protocol could also be used to prepare a chiral tribenzoselenepin.

Enantioselective sp3 C–H alkylation of γ-butyrolactam by a chiral Ir(I) catalyst for the synthesis of 4-substituted γ-amino acids

Co-reporter:Yu-ki Tahara, Masamichi Michino, Mamoru Ito, Kyalo Stephen Kanyiva and Takanori Shibata

Chemical Communications 2015 vol. 51(Issue 93) pp:16660-16663

Publication Date(Web):21 Sep 2015

DOI:10.1039/C5CC07102J

Ir-catalyzed sp3 C–H alkylation of γ-butyrolactam with alkenes was used for the highly enantioselective synthesis of 5-substituted γ-lactams, which were readily converted into chiral 4-substituted γ-amino acids. A broad scope of alkenes was amenable as coupling partners, and the alkylated product using acrylate could be transformed into the key intermediate of pyrrolam A synthesis.

Enantioselective synthesis of planar-chiral benzosiloloferrocenes by Rh-catalyzed intramolecular C–H silylation

Co-reporter:Takanori Shibata, Tsubasa Shizuno and Tomoya Sasaki

Chemical Communications 2015 vol. 51(Issue 37) pp:7802-7804

Publication Date(Web):06 Feb 2015

DOI:10.1039/C5CC00723B

The first synthesis of planar-chiral benzosiloloferrocenes was achieved by the intramolecular reaction of 2-(dimethylhydrosilyl)arylferrocenes. The enantioselective cross dehydrogenative coupling of an sp2 C–H bond of ferrocene with a Si–H bond proceeded efficiently with the use of a Rh-chiral diene catalyst.

Inside Cover: Iridium-Catalyzed Intramolecular Enantioselective CH Alkylation at the C-2 Position of N-Alkenylindoles (Adv. Synth. Catal. 6/2015)

Co-reporter:Takanori Shibata;Naoto Ryu;Hideaki Takano

Advanced Synthesis & Catalysis 2015 Volume 357( Issue 6) pp:

Publication Date(Web):

DOI:10.1002/adsc.201500271

Very Important Publication: Iridium-Catalyzed Intramolecular Enantioselective CH Alkylation at the C-2 Position of N-Alkenylindoles

Co-reporter:Takanori Shibata;Naoto Ryu;Hideaki Takano

Advanced Synthesis & Catalysis 2015 Volume 357( Issue 6) pp:1131-1135

Publication Date(Web):

DOI:10.1002/adsc.201401163

Total Synthesis of cis-Clavicipitic Acid from Asparagine via Ir-Catalyzed CH bond Activation as a Key Step

Co-reporter:Yu-ki Tahara;Mamoru Ito;Dr. Kyalo Stephen Kanyiva;Dr. Takanori Shibata

Chemistry - A European Journal 2015 Volume 21( Issue 32) pp:11340-11343

Publication Date(Web):

DOI:10.1002/chem.201502300

Abstract

4-Substituted tryptophan derivatives and the total synthesis of cis-clavicipitic acid were achieved in reactions in which Ir-catalyzed CH bond activation was a key step. The starting material for these reactions is asparagine, which is a cheap natural amino acid. The reductive amination step from the 4-substituted tryptophan derivative gave cis-clavicipitic acid with perfect diastereoselectivity.

Asymmetric synthesis of multi-substituted triptycenes via enantioselective alkynylation of 1,5-dibromoanthracene-9,10-dione

Co-reporter:Takanori Shibata, Yuri Kamimura

Tetrahedron: Asymmetry 2015 Volume 26(Issue 1) pp:41-45

Publication Date(Web):15 January 2015

DOI:10.1016/j.tetasy.2014.11.012

Enantioselective alkynylation of 1,5-dibromoanthracene-9,10-dione by alkynyllithium reagents prepared from alkynes, n-BuLi, and sparteine gave chiral cis-diols possessing two alkyne moieties with moderate ee. Subsequent Ru-catalyzed [2+2+2] cycloaddition of the diol with alkynes afforded chiral 1,5-dibromotriptycenes.cis-1,5-Dibromo-9,10-bis(phenylethynyl)-9,10-dihydroanthracene-9,10-diolC30H18Br2O2Ee = 58% from HPLC[α]D26 = −128 (c 0.70, CHCl3)Source of chirality: (+)-sparteineAbsolute configuration: not determinedcis-1,5-Dibromo-9,10-dihydro-9,10-bis[2-(4-methoxyphenyl)ethynyl]anthracene-9,10-diolC32H22Br2O2Ee = 55% from HPLC[α]D26 = −112 (c 0.67, CHCl3)Source of chirality: (+)-sparteineAbsolute configuration: not determinedcis-1,5-Dibromo-9,10-bis(2-(4-chlorophenyl)ethynyl)-9,10-dihydroanthracene-9,10-diolC30H16Br2Cl2O2Ee = 60% from HPLC[α]D26 = −119 (c 0.37, CHCl3)Source of chirality: (+)-sparteineAbsolute configuration: not determined2,3-Bis(hydroxymethyl)-5,13-bis(4-methoxyphenyl)-1,4-diphenyl-9,10-dihydro-9,10-[1,2]benzenoanthracene-9,10-diolC48H38O6[α]Hg43526 = +23.4 (c 0.49, CHCl3)Source of chirality: (+)-sparteineAbsolute configuration: not determinedcis-1,5-Dibromo-9,10-di(hex-1-ynyl)-9,10-dihydroanthracene-9,10-diolC30H16Br2Cl2O2Ee = 50% from HPLC[α]D26 = −87.2 (c 0.62, CHCl3)Source of chirality: (+)-sparteineAbsolute configuration: not determined5,13-Dibromo-2-butyl-1,4-diphenyl-9,10-dihydro-9,10-[1,2]benzenoanthraceneC36H28Br2O2Ee = 58% from HPLC[α]Hg43526 = −212 (c 0.20, CHCl3)Source of chirality: (+)-sparteineAbsolute configuration: not determined5,13-Dibromo-2-hexyl-1,4-diphenyl-9,10-dihydro-9,10-[1,2]benzenoanthraceneC38H32Br2O2Ee = 58% from HPLC[α]Hg43526 = −216 (c 0.21, CHCl3)Source of chirality: (+)-sparteineAbsolute configuration: not determined5,13-Dibromo-2,3-bis(hydroxymethyl)-1,4-diphenyl-9,10-dihydro-9,10-[1,2]benzenoanthracene-9,10-diolC34H24Br2O4Ee = 58% from HPLC[α]Hg43526 = −17.0 (c 0.85, CHCl3)Source of chirality: (+)-sparteineAbsolute configuration: not determined

Catalytic [2 + 2 + 2] Cycloaddition of Benzothiophene Dioxides with α,ω-Diynes for the Synthesis of Condensed Polycyclic Compounds

Co-reporter:Yu-ki Tahara, Manami Gake, Riku Matsubara, and Takanori Shibata

Organic Letters 2014 Volume 16(Issue 22) pp:5980-5983

Publication Date(Web):November 10, 2014

DOI:10.1021/ol5030019

A Rh-catalyzed intermolecular [2 + 2 + 2] cycloaddition of the 2,3-double bond of benzothiophene dioxides with α,ω-diynes gave sulfone-containing cycloadducts in high yields. This is the first example of a catalytic [2 + 2 + 2] cycloaddition that uses the 2,3-double bond of a heterole as an ene moiety. The consecutive reaction of benzodithiophene tetraoxide with 2,3-naphthylene-tethered 1,7-diyne gave an 11-ring condensed polycyclic compound in one pot.

Iridium(I)-Catalyzed Direct CH Bond Alkylation of the C-7 Position of Indolines with Alkenes

Co-reporter:Shiguang Pan;Naoto Ryu

Advanced Synthesis & Catalysis 2014 Volume 356( Issue 5) pp:929-933

Publication Date(Web):

DOI:10.1002/adsc.201300917

Directed CH Alkenylation of Quinoline N-Oxides at the C-8 Position Using a Cationic Rhodium(I) Catalyst

Co-reporter:Takanori Shibata;Yusuke Matsuo

Advanced Synthesis & Catalysis 2014 Volume 356( Issue 7) pp:1516-1520

Publication Date(Web):

DOI:10.1002/adsc.201400223

Synthesis of Multicyclic Heterocycles Initiated by CH Bond Activation Along with Rollover Using a Rh(III) Catalyst

Co-reporter:Takanori Shibata;Satoshi Takayasu

Heteroatom Chemistry 2014 Volume 25( Issue 5) pp:379-388

Publication Date(Web):

DOI:10.1002/hc.21158

ABSTRACT

Various multicyclic heterocycles were synthesized via “rollover” as the key pathway using a Rh(III) catalyst with a catalytic amount of sodium pivalate or copper(II) acetate. 3-Alkynyl-2-heteroarylpyridines were transformed into tri- or tetracyclic heterocycles containing two heteroatoms via an intramolecular alkyne insertion. 3-Aryloyl-2-arylpyridines were derived into 4-azafluoren-9-ols via the intramolecular carbonyl insertion.

Ir(III)-Catalyzed C7-Position-Selective Oxidative CH Alkenylation of Indolines with Alkenes in Air

Co-reporter:Dr. Shiguang Pan;Takayuki Wakaki;Naoto Ryu;Dr. Takanori Shibata

Chemistry – An Asian Journal 2014 Volume 9( Issue 5) pp:1257-1260

Publication Date(Web):

DOI:10.1002/asia.201301733

Abstract

An efficient method for C7-position-selective alkenylation of N-substituted indolines with alkenes is reported. Various 7-alkenylindolines were obtained in moderate to excellent yields in air in the presence of catalytic amounts of [Cp*IrCl₂]₂, AgOTf, and Cu(OAc)₂. The protocol relies on the use of a carbonyl or carbamoyl group on the nitrogen atom of indoline as a directing group and is potentially applicable to the synthesis of 7-alkenylindoles and 7-alkylindoles.

Iridium-Catalyzed Enantioselective CH Alkylation of Ferrocenes with Alkenes Using Chiral Diene Ligands

Co-reporter:Dr. Takanori Shibata;Tsubasa Shizuno

Angewandte Chemie International Edition 2014 Volume 53( Issue 21) pp:5410-5413

Publication Date(Web):

DOI:10.1002/anie.201402518

Abstract

The first catalytic and enantioselective CH alkylation of ferrocene derivatives with various alkenes was achieved. A cationic iridium complex, having a chiral diene ligand, and an isoquinolyl moiety as a directing group are essential for regioselective and enantioselective CH bond activation.

Iridium-Catalyzed Enantioselective CH Alkylation of Ferrocenes with Alkenes Using Chiral Diene Ligands

Co-reporter:Dr. Takanori Shibata;Tsubasa Shizuno

Angewandte Chemie 2014 Volume 126( Issue 21) pp:5514-5517

Publication Date(Web):

DOI:10.1002/ange.201402518

Abstract

The first catalytic and enantioselective CH alkylation of ferrocene derivatives with various alkenes was achieved. A cationic iridium complex, having a chiral diene ligand, and an isoquinolyl moiety as a directing group are essential for regioselective and enantioselective CH bond activation.

Synthesis of macrocyclic heteroarylenes by consecutive inter- and intramolecular cycloadditions of thiophenylene-tethered triynes

Co-reporter:Takanori Shibata, Masako Fujimoto, Takashi Otani

Tetrahedron 2014 70(45) pp: 8453-8461

Publication Date(Web):

DOI:10.1016/j.tet.2014.09.077

Recent Advances in Iridium-Catalyzed Alkylation of C–H and N–H Bonds

Co-reporter:Shiguang Pan and Takanori Shibata

ACS Catalysis 2013 Volume 3(Issue 4) pp:704

Publication Date(Web):March 5, 2013

DOI:10.1021/cs400066q

Over the past few years, iridium complexes have been widely used in the direct functionalization of unactivated bonds. In the presence of iridium catalysts, inactive C–H and N–H bonds have been transformed into C–C and N–C bonds in dehydrative alkylation using alcohols, allylation using allyl carbonates, and alkylation using alkenes. Enantioselective variants of some reactions have also been reported.Keywords: alcohols; alkenes; alkylation; carbonates; iridium

Ir(I)-Catalyzed Synthesis of N-Substituted Pyridones from 2-Alkoxypyridines via C–O Bond Cleavage

Co-reporter:Shiguang Pan, Naoto Ryu, and Takanori Shibata

Organic Letters 2013 Volume 15(Issue 8) pp:1902-1905

Publication Date(Web):March 29, 2013

DOI:10.1021/ol400557z

A cationic Ir(I) complex-catalyzed O-to-N-alkyl migration in 2-alkoxypyridines bearing a secondary alkyl group on the oxygen atom by C–O bond cleavage is described. The present transformation gave various N-alkylpyridones in moderate to good yields. The addition of sodium acetate played a key role in suppressing β-hydrogen elimination.

Effect of Multinuclear Copper/Aluminum Complexes in Highly Asymmetric Conjugate Addition of Trimethylaluminum to Acyclic Enones

Co-reporter:Dr. Kohei Endo;Daisuke Hamada;Sayuri Yakeishi;Dr. Takanori Shibata

Angewandte Chemie International Edition 2013 Volume 52( Issue 2) pp:606-610

Publication Date(Web):

DOI:10.1002/anie.201206297

Ir(I)-Catalyzed C–H Bond Alkylation of C2-Position of Indole with Alkenes: Selective Synthesis of Linear or Branched 2-Alkylindoles

Co-reporter:Shiguang Pan ; Naoto Ryu

Journal of the American Chemical Society 2012 Volume 134(Issue 42) pp:17474-17477

Publication Date(Web):October 9, 2012

DOI:10.1021/ja308742x

A cationic iridium-catalyzed C2-alkylation of N-substituted indole derivatives with various alkenes has been developed, which selectively gives linear or branched 2-alkylindoles in high to excellent selectivity. This protocol relies on the use of the carbonyl group on the nitrogen atom of indole as a directing group: a linear product was predominant when an acetyl group was used as a directing group, and a branched product was predominant with a benzoyl group.

Multinuclear Cu-Catalysts Based on SPINOL-PHOS in Asymmetric Conjugate Addition of Organozinc Reagents

Co-reporter:Kohei Endo, Daisuke Hamada, Sayuri Yakeishi, Mika Ogawa, and Takanori Shibata

Organic Letters 2012 Volume 14(Issue 9) pp:2342-2345

Publication Date(Web):April 20, 2012

DOI:10.1021/ol300748d

Multinuclear Cu/Zn complex-catalyzed efficient asymmetric conjugate addition of organozinc reagents to acyclic and cyclic enones has been developed in the presence of a wide variety of regioisomeric chiral diols bearing phosphorus moieties as ligands. The regioisomeric SPINOL-PHOS ligands based on a SPINOL architecture showed an unexpected inversion of stereoselectivity.

Ir(I)-Catalyzed Intermolecular Regio- and Enantioselective Hydroamination of Alkenes with Heteroaromatic Amines

Co-reporter:Shiguang Pan, Kohei Endo, and Takanori Shibata

Organic Letters 2012 Volume 14(Issue 3) pp:780-783

Publication Date(Web):January 18, 2012

DOI:10.1021/ol203318z

A cationic Ir(I)-C3-TUNEPHOS complex catalyzed an intermolecular hydroamination of styrene derivatives with various heteroaromatic amines. The reaction gave Markovnikov products with perfect regioselectivity and good enantioselectivity under solvent-free conditions.

Highly enantioselective synthesis of silahelicenes using Ir-catalyzed [2+2+2] cycloaddition

Co-reporter:Takanori Shibata, Toshifumi Uchiyama, Yusuke Yoshinami, Satoshi Takayasu, Kyoji Tsuchikama and Kohei Endo

Chemical Communications 2012 vol. 48(Issue 9) pp:1311-1313

Publication Date(Web):21 Nov 2011

DOI:10.1039/C1CC16762F

Silahelicenes, which contain two silole moieties in a helically chiral structure, were synthesized by a chiral Ir-catalyzed intermolecular [2+2+2] cycloaddition of tetraynes with diynes along with a Ni-mediated intramolecular [2+2+2] cycloaddition. The photophysical properties of the obtained highly enantiomerically enriched silahelicenes (up to 93% ee) were also measured.

Rh(III)-Catalyzed C–H Bond Activation along with “Rollover” for the Synthesis of 4-Azafluorenes

Co-reporter:Takanori Shibata, Satoshi Takayasu, Shun Yuzawa, and Takashi Otani

Organic Letters 2012 Volume 14(Issue 19) pp:5106-5109

Publication Date(Web):September 17, 2012

DOI:10.1021/ol302375c

An intramolecular reaction of 3-alkynyl and 3-alkenyl-2-arylpyridines selectively gave 4-azafluorene compounds in the presence of a catalytic amount of [Cp*RhCl2]2 and Cu(OAc)2. Pyridine-directed C–H bond activation along with “rollover” are likely to be key steps of this transformation.

Ru-catalyzed β-selective and enantioselective addition of amines to styrenes initiated by direct arene-exchange

Co-reporter:Maiko Otsuka, Hiroya Yokoyama, Kohei Endo and Takanori Shibata

Organic & Biomolecular Chemistry 2012 vol. 10(Issue 19) pp:3815-3818

Publication Date(Web):27 Mar 2012

DOI:10.1039/C2OB25457C

A catalytic β-selective addition of amines to styrenes proceeded in the presence of cationic Ru complexes combined with diphosphine ligands. In the reaction of α-methylstyrene, an enantioselective addition was achieved by using xylylBINAP.

One-Pot Synthesis of Symmetrical and Unsymmetrical Diarylmethanes via Diborylmethane

Co-reporter:Kohei Endo, Takafumi Ishioka, Takahiro Ohkubo, and Takanori Shibata

The Journal of Organic Chemistry 2012 Volume 77(Issue 17) pp:7223-7231

Publication Date(Web):August 17, 2012

DOI:10.1021/jo3015165

A one-pot synthesis of diarylmethanes from air-stable diborylmethane via the Suzuki–Miyaura cross-coupling reaction is described. The present approach realizes the synthesis of various symmetrical and unsymmetrical diarylmethanes in good to excellent yields.

Cross Coupling between sp3-Carbon and sp3-Carbon Using a Diborylmethane Derivative at Room Temperature

Co-reporter:Kohei Endo, Takahiro Ohkubo, Takafumi Ishioka, and Takanori Shibata

The Journal of Organic Chemistry 2012 Volume 77(Issue 10) pp:4826-4831

Publication Date(Web):April 27, 2012

DOI:10.1021/jo3004293

A novel example of the Suzuki–Miyaura cross-coupling reaction between sp3-carbon and sp3-carbon is described. The reaction of a diborylmethane derivative with allyl halides or benzyl halides proceeded efficiently in the presence of appropriate Pd-catalysts at room temperature. The present approaches provide functionalized homoallylboronates and alkylboronates with excellent regio- and chemoselectivities.

Enantioselective synthesis of tripodal cyclophanes and pyridinophanes by intramolecular [2+2+2] cycloaddition

Co-reporter:Takanori Shibata, Mayu Miyoshi, Toshifumi Uchiyama, Kohei Endo, Nobuaki Miura, Kenji Monde

Tetrahedron 2012 68(12) pp: 2679-2686

Publication Date(Web):

DOI:10.1016/j.tet.2012.01.046

Reversal in enantioselectivity induced by achiral alcohols in asymmetric autocatalysis in the presence of a chiral diol as a chiral initiator

Co-reporter:Takanori Shibata, Hikaru Tarumi, Tsuneomi Kawasaki, Kenso Soai

Tetrahedron: Asymmetry 2012 Volume 23(Issue 14) pp:1023-1027

Publication Date(Web):31 July 2012

DOI:10.1016/j.tetasy.2012.07.010

A reversal in enantioselectivity was observed by the combination of a chiral diol and achiral alcohols as a chiral initiator in the asymmetric alkylation of a pyrimidine-5-carbaldehyde using diisopropylzinc. (2S,3S)-Butane-2,3-diol alone induced (R)-pyrimidyl alkanol, while a mixture of the chiral diol and phenol derivatives induced (S)-pyrimidyl alkanol. The effect of achiral alcohols is also discussed.

Cationic iridium-catalyzed enantioselective activation of secondary sp3 C–H bond adjacent to nitrogen atom

Co-reporter:Shiguang Pan, Yusuke Matsuo, Kohei Endo, Takanori Shibata

Tetrahedron 2012 68(44) pp: 9009-9015

Publication Date(Web):

DOI:10.1016/j.tet.2012.08.071

Asymmetric ortho-lithiation of 1,n-dioxa[n]paracyclophane derivatives for the generation of planar chirality

Co-reporter:Kazumasa Kanda, Risa Hamanaka, Kohei Endo, Takanori Shibata

Tetrahedron 2012 68(5) pp: 1407-1416

Publication Date(Web):

DOI:10.1016/j.tet.2011.12.031

[Ir(cod)2]BARF-Catalyzed C–H Bond Alkenylation and Alkylation of Ferrocenes

Co-reporter:Satoshi Takebayashi

Organometallics 2012 Volume 31(Issue 11) pp:4114-4117

Publication Date(Web):May 22, 2012

DOI:10.1021/om300348e

[Ir(cod)2]BARF [BARF = tetrakis(3,5-trifluoromethylphenyl)borate] catalyzed the directed alkenylation and alkylation of ferrocenes to form a variety of tri- and disubstituted ferrocenes. Mechanistic investigation revealed several putative intermediates along with the importance of COD (1,5-cyclooctadiene), as a diene ligand, and a possible catalyst deactivation pathway. On the basis of the mechanistic investigation, catalytic activity was further improved.

Multinuclear Pd/Zn Complex-Catalyzed Asymmetric Alkylative Ring-Opening Reaction of Oxabicyclic Alkenes

Co-reporter:Kohei Endo, Keisuke Tanaka, Mika Ogawa, and Takanori Shibata

Organic Letters 2011 Volume 13(Issue 5) pp:868-871

Publication Date(Web):January 24, 2011

DOI:10.1021/ol102928q

A multinuclear palladium catalyst can be used to realize the efficient catalytic asymmetric alkylative ring-opening reaction of oxabicyclic alkenes using dimethylzinc. The use of (R)-BINOL-PHOS bearing bisphosphine and diol moieties is essential for achieving excellent catalytic performance; the corresponding monophosphine and hydroxy-protected derivatives showed lower catalytic activities and/or enantioselectivities. The generation of Pd/Zn-multinuclear complexes is a key feature of the present catalysis.

Chiral Rh- and Ir-catalyzed intramolecular cycloaddition of hexaynes for the construction of new chiral skeletons

Co-reporter:Takanori Shibata;Tatsuya Chiba;Hiroyuki Hirashima;Yasunori Ueno;Kohei Endo

Heteroatom Chemistry 2011 Volume 22( Issue 3-4) pp:363-370

Publication Date(Web):

DOI:10.1002/hc.20691

Abstract

Enantioselective intramolecular cycloaddition of hexaynes with 1,3-diyne moiety was examined. Chiral Rh catalyst provided axially chiral 1,1′ -bis(biphenylenyl) derivatives by consecutive [2+2+2] cycloaddition. In contrast, chiral Ir catalyst provided axially chiral macrocyclic compounds with 1,3-diyne moiety by single [2+2+2] cycloaddition. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 22:363–370, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/hc.20691

Regioselective Addition of Various Heteronucleophiles to (Styrene)Cr(CO)3 Complexes

Co-reporter:Maiko Otsuka, Kohei Endo, and Takanori Shibata

Organometallics 2011 Volume 30(Issue 13) pp:3683-3685

Publication Date(Web):June 7, 2011

DOI:10.1021/om200268v

(Styrene)Cr(CO)3 complexes underwent the addition of various heteronucleophiles such as alcohols, amines, and thiols, in the presence of KOH, and the β-addition products were selectively obtained in moderate to excellent yields. The structural details and features of the product complexes were also elucidated.

Catalytic SNAr reaction of non-activated fluoroarenes with amines via Ru η6-arene complexes

Co-reporter:Maiko Otsuka, Kohei Endo and Takanori Shibata

Chemical Communications 2010 vol. 46(Issue 2) pp:336-338

Publication Date(Web):26 Nov 2009

DOI:10.1039/B919413D

Ru-catalyzed SNAr reaction of non-activated fluoroarenes with secondary amines proceeded through η6-arene complexes to give aminated products in up to 79% yield.

Enantioselective Synthesis of Planar-Chiral 1,n-Dioxa[n]paracyclophanes via Catalytic Asymmetric ortho-Lithiation

Co-reporter:Kazumasa Kanda, Kohei Endo and Takanori Shibata

Organic Letters 2010 Volume 12(Issue 9) pp:1980-1983

Publication Date(Web):March 29, 2010

DOI:10.1021/ol100444u

Highly enantioselective ortho-lithiation and dilithiation of 1,n-dioxa[n]paracyclophanes were realized with the use of sec-butyllithium and a catalytic or stoichiometric amount of sparteine. Quenching with various electrophiles, such as iodine, iodomethane, and chlorodiphenylphosphine, afforded chiral mono- and disubstituted paracyclophanes with good to excellent ee.

Stereoselective Synthesis of Tetrasubstituted Alkenylboronates via 1,1-Organodiboronates

Co-reporter:Kohei Endo, Munenao Hirokami and Takanori Shibata

The Journal of Organic Chemistry 2010 Volume 75(Issue 10) pp:3469-3472

Publication Date(Web):April 15, 2010

DOI:10.1021/jo1003407

The stereoselective synthesis of tetrasubstituted alkenylboronates was established via the lithiation/nucleophilic addition reaction of 1,1-organodiboronates to carbonyl compounds. The present approach enables the facile and practical synthesis of tetrasubstituted olefins, which are useful synthetic intermediates for further functionalizations.

Multinuclear Catalyst for Copper-Catalyzed Asymmetric Conjugate Addition of Organozinc Reagents

Co-reporter:Kohei Endo Dr.;Mika Ogawa Dr.

Angewandte Chemie International Edition 2010 Volume 49( Issue 13) pp:2410-2413

Publication Date(Web):

DOI:10.1002/anie.200906839

Cationic Ir(I)-Catalyzed sp3 C−H Bond Alkenylation of Amides with Alkynes

Co-reporter:Kyoji Tsuchikama, Mitsugu Kasagawa, Kohei Endo and Takanori Shibata

Organic Letters 2009 Volume 11(Issue 8) pp:1821-1823

Publication Date(Web):March 18, 2009

DOI:10.1021/ol900404r

A cationic Ir(I)-BINAP catalyst cleaved sp3 C−H bonds of arylamides rather than sp2 C−H bonds, which was followed by alkenylation with alkynes to give allylamides. Several types of amides and alkynes were suitable as substrates, and the corresponding allylamides were obtained in moderate to good yield. We also demonstrated that carbonyl-directed sp3 C−H bond cleavage would be an initial step in the present reaction by a deuterium-labeling experiment.

Enantioselective Synthesis of Chiral Tripodal Cage Compounds by [2 + 2 + 2] Cycloaddition of Branched Triynes

Co-reporter:Takanori Shibata, Toshifumi Uchiyama and Kohei Endo

Organic Letters 2009 Volume 11(Issue 17) pp:3906-3908

Publication Date(Web):August 10, 2009

DOI:10.1021/ol9014893

Cyclotrimerization of triynes branched by a nitrogen atom of 2-aminophenol yielded planar-chiral tripodal cage compounds. When a cationic Rh−Me-DUPHOS catalyst was used, the cycloadducts were obtained in high yield and excellent ee, and a macrocyclic compound with a [15]cyclophane system was also obtained. This method can be further applied to the synthesis of a triarmed pyridinophane by the intramolecular reaction of a diyne−nitrile.

The first asymmetric Sonogashira coupling for the enantioselective generation of planar chirality in paracyclophanes

Co-reporter:Kazumasa Kanda, Tamami Koike, Kohei Endo and Takanori Shibata

Chemical Communications 2009 (Issue 14) pp:1870-1872

Publication Date(Web):24 Feb 2009

DOI:10.1039/B818904H

The double Sonogashira coupling of diiodoparacyclophanes with alkynes proceeded to give planarly chiral dialkynylparacyclophanes; a chiral Pd catalyst, which was prepared in situ from PdCl2(CH3CN)2 and Taniaphos, realized the first asymmetric Sonogashira coupling with up to ca. 80% ee.

Iridium-Catalyzed Selective Synthesis of 4-Substituted Benzofurans and Indoles via Directed Cyclodehydration

Co-reporter:Kyoji Tsuchikama;Yu-ki Hashimoto;Kohei Endo

Advanced Synthesis & Catalysis 2009 Volume 351( Issue 17) pp:2850-2854

Publication Date(Web):

DOI:10.1002/adsc.200900570

Abstract

A directed cyclization-dehydration cascade of α-aryloxy ketones and α-arylamino ketones was efficiently catalyzed by a cationic iridium-BINAP complex, which afforded various types of 4-substituted benzofurans and indoles in high yields with complete regioselectivity. The newly developed protocol also enabled the enantioselective preparation of chiral 4-acetyloxindole using a chiral iridium catalyst.

Catalytic Enantioselective Synthesis of Chiral Tetraphenylenes: Consecutive Inter- and Intramolecular Cycloadditions of Two Triynes

Co-reporter:Takanori Shibata Dr.;Tatsuya Chiba;Hiroyuki Hirashima;Yasunori Ueno ;Kohei Endo Dr.

Angewandte Chemie International Edition 2009 Volume 48( Issue 43) pp:8066-8069

Publication Date(Web):

DOI:10.1002/anie.200903715

Catalytic Enantioselective Synthesis of Chiral Tetraphenylenes: Consecutive Inter- and Intramolecular Cycloadditions of Two Triynes

Co-reporter:Takanori Shibata Dr.;Tatsuya Chiba;Hiroyuki Hirashima;Yasunori Ueno ;Kohei Endo Dr.

Angewandte Chemie 2009 Volume 121( Issue 43) pp:8210-8213

Publication Date(Web):

DOI:10.1002/ange.200903715

Rh-catalyzed intermolecular and enantioselective [4 + 2] cycloaddition of 1,3-dienes with dimethyl acetylenedicarboxylate

Co-reporter:Takanori Shibata, Daisuke Fujiwara and Kohei Endo

Organic & Biomolecular Chemistry 2008 vol. 6(Issue 3) pp:464-467

Publication Date(Web):11 Dec 2007

DOI:10.1039/B717914F

A Rh-BINAP complex catalyzed an intermolecular and enantioselective [4 + 2] cycloaddition of 1-monosubstituted, 1,1- or 1,2-disubstituted buta-1,3-dienes with dimethyl acetylenedicarboxylate to give chiral cyclohexa-1,4-dienes.

Highly diastereo- and enantioselective construction of both central and axial chiralities by Rh-catalyzed [2 + 2 + 2] cycloaddition

Co-reporter:Takanori Shibata, Mayumi Otomo, Yu-ki Tahara and Kohei Endo

Organic & Biomolecular Chemistry 2008 vol. 6(Issue 23) pp:4296-4298

Publication Date(Web):15 Oct 2008

DOI:10.1039/B814014F

The cationic Rh–SEGPHOS complex catalyzed an intermolecular [2 + 2 + 2] cycloaddition of enynes, possessing an ortho-substituted aryl group on their alkyne terminus, with acetylenedicarboxylates. Bicyclic cyclohexa-1,3-dienes with both central and axial chiralities were obtained in extremely highly diastereo- and enantioselective manner.

Carbonylative and Hydrosilylative Carbocyclization of 1,5-Diynes for the Synthesis of Cyclic Dienones

Co-reporter:Takanori Shibata, Naohisa Nakagawa, Yasunori Ueno and Kohei Endo

Organometallics 2008 Volume 27(Issue 6) pp:1342-1344

Publication Date(Web):February 27, 2008

DOI:10.1021/om7012277

A rhodium complex, [Rh(acac)(CO)2], has been identified to catalyze the cyclization of various 1,5-diynes with hydrosilanes under an atmospheric pressure of carbon monoxide at room temperature. The cyclization of 1,5-diynes proceeds along with hydrosilylation and carbonylation to give derivatives of 2,5-dialkylidenecyclopentanone.

Counteranion-Accelerated RhIOAc-Catalyzed Regioselective Hydroboration of Vinylarenes

Co-reporter:Kohei Endo, Munenao Hirokami and Takanori Shibata

Organometallics 2008 Volume 27(Issue 20) pp:5390-5393

Publication Date(Web):September 20, 2008

DOI:10.1021/om800465q

RhIOAc shows a remarkably high catalytic activity for the hydroboration of vinylarenes with pinacolborane. The reaction was complete within 10 min to give the Markovnikov product.

Chiral secondary alcohol-induced asymmetric autocatalysis: correlation between the absolute configuration of the chiral initiators and the product

Co-reporter:Takanori Shibata, Kimiko Iwahashi, Tsuneomi Kawasaki, Kenso Soai

Tetrahedron: Asymmetry 2007 Volume 18(Issue 15) pp:1759-1762

Publication Date(Web):9 August 2007

DOI:10.1016/j.tetasy.2007.07.030

In the presence of various chiral secondary alcohols as chiral initiators, an enantioselective alkylation of a pyrimidine-5-carbaldehyde using diisopropylzinc was examined: a pyrimidyl alkanol was obtained in high yield and enantiomeric excess. The correlation between the absolute configuration of the chiral secondary alcohols and the pyrimidyl alkanol is discussed.3,3-Dimethyl-1-phenylbutan-1-olC12H18OEe = 95.5% (HPLC, Chiralpak OD–H)[α]D28=+61.9 (c 0.10, CHCl3)Source of chirality: resolutionAbsolute configuration: modified Mosher method4,4-Dimethyl-1-phenylpentan-2-olC13H20OEe = 96.6% (HPLC, Chiralpak OD–H)[α]D23=+5.9 (c 0.47, CHCl3)Source of chirality: resolutionAbsolute configuration: modified Mosher method

Recent Advances in the Catalytic Pauson–Khand-Type Reaction

Co-reporter:Takanori Shibata

Advanced Synthesis & Catalysis 2006 Volume 348(Issue 16-17) pp:

Publication Date(Web):27 NOV 2006

DOI:10.1002/adsc.200600328

The Pauson–Khand-type reaction is formally a [2+2+1] cycloaddition involving an alkyne, an alkene and carbon monoxide catalyzed or mediated by transition metal complexes. This review focuses on the catalytic reaction and describes the recent research on the Pauson–Khand-type reaction.

Iridium-Catalyzed Enantioselective [2+2+2] Cycloaddition of Diynes and Monoalkynes for the Generation of Axial Chiralities

Co-reporter:Takanori Shibata;Yoshikazu Arai;Kyoko Takami;Kyoji Tsuchikama;Takayoshi Fujimoto;Satoshi Takebayashi;Kentaro Takagi

Advanced Synthesis & Catalysis 2006 Volume 348(Issue 16-17) pp:

Publication Date(Web):27 NOV 2006

DOI:10.1002/adsc.200600317

A highly enantioselective intermolecular [2+2+2] cycloaddition of alkynes was catalyzed by a chiral iridium complex. Symmetrical and unsymmetrical diynes, and monoalkynes possessing functional group(s) were subjected to the reaction and various types of axially chiral compounds possessing biaryl skeletons were obtained in good to excellent enantiomeric excesses.

Enantioselective intramolecular [2+2+2] cycloaddition of triynes for the synthesis of atropisomeric chiral ortho-diarylbenzene derivatives

Co-reporter:Takanori Shibata, Kyoji Tsuchikama, Maiko Otsuka

Tetrahedron: Asymmetry 2006 Volume 17(Issue 4) pp:614-619

Publication Date(Web):20 February 2006

DOI:10.1016/j.tetasy.2005.12.033

An iridium-chiral diphosphine complex was used to catalyze an enantioselective [2+2+2] cycloaddition of oxygen- and nitrogen-bridged triynes with ortho-substituted aryl groups on their termini. ortho-Diarylbenzenes with atropisomeric chiralities were obtained in high yield and enantiomeric excess.(−)-4,5-Di(napthalen-1-yl)-1,3,6,8-tetrahydro-2,7-dioxaas-indaceneC30H22O2Ee = 90%[α]D29=-347.9 (c 1.7, CHCl3)Source of chirality: (S,S)-MeDUPHOSAbsolute configuration: not determined(−)-4,5-Di(anthracen-1-yl)-1,3,6,8-tetrahydro-2,7-dioxaas-indaceneC38H26O2Ee = 87%[α]D23=-604.3 (c 0.19, CHCl3)Source of chirality: (S,S)-MeDUPHOSAbsolute configuration: not determined(−)-4,5-Di(phenanthren-9-yl)-1,3,6,8-tetrahydro-2,7-dioxaas-indaceneC38H26O2Ee = 87%[α]D23=-120.6 (c 0.79, CHCl3)Source of chirality: (S,S)-MeDUPHOSAbsolute configuration: not determined(−)-4,5-Bis(4-methoxynaphthalen-1-yl)-1,3,6,8-tetrahydro-2,7-dioxaas-indaceneC32H26O4Ee = 90%[α]D24=-282.8 (c 1.8, CHCl3)Source of chirality: (S,S)-MeDUPHOSAbsolute configuration: not determined(−)-4,5-Bis(4-methoxy-2-methylphenyl)-1,3,6,8-tetrahydro-2,7-dioxaas-indaceneC26H26O4Ee = 95%[α]D21=-31.6 (c 0.61, CHCl3)Source of chirality: (S,S)-MeDUPHOSAbsolute configuration: not determined(−)-4,5-Bis(2-chloro-4-nitrophenyl)-1,3,6,8-tetrahydro-2,7-dioxaas-indaceneC22H14Cl2N2O6Ee = 90%[α]D21=-116.9 (c 1.8, CHCl3)Source of chirality: (S,S)-MeDUPHOSAbsolute configuration: (S,S)(−)-4,5-Bis(4-methoxynaphthalen-1-yl)-2,7-bis(p-toluenesulfonyl)-1,3,6,8-tetrahydro-2,7-diazaas-indaceneC46H40N2O6S2Ee = ca. 95%[α]D21=-258.8 (c 0.54, CHCl3)Source of chirality: (S,S)-MeDUPHOSAbsolute configuration: not determined

Ir-catalyzed almost perfect enantioselective synthesis of helical polyaryls based on an axially-chiral sequence

Co-reporter:Takanori Shibata and Kyoji Tsuchikama

Chemical Communications 2005 (Issue 48) pp:6017-6019

Publication Date(Web):04 Nov 2005

DOI:10.1039/B513124C

Ir-catalyzed enantioselective [2 + 2 + 2] cycloaddition of tetraynes or an octayne with monoalkynes proceeded to give helically-chiral quinquearyl and noviaryl compounds, which respectively have four and eight consecutive axial chiralities, in an almost enantiomerically pure form.

Chemoselective and Regiospecific Suzuki Coupling on a Multisubstituted sp3-Carbon in 1,1-Diborylalkanes at Room Temperature

Co-reporter:Kohei Endo ; Takahiro Ohkubo ; Munenao Hirokami

Journal of the American Chemical Society () pp:

Publication Date(Web):July 26, 2010

DOI:10.1021/ja105176v

The palladium-catalyzed Suzuki−Miyaura cross-coupling on a multisubstituted sp3-carbon in 1,1-diborylalkanes was achieved at room temperature. The generation of a monoborate intermediate by virtue of the adjacent B atom could result in the chemoselective coupling reaction under ambient conditions.

Highly diastereo- and enantioselective construction of both central and axial chiralities by Rh-catalyzed [2 + 2 + 2] cycloaddition

Co-reporter:Takanori Shibata, Mayumi Otomo, Yu-ki Tahara and Kohei Endo

Organic & Biomolecular Chemistry 2008 - vol. 6(Issue 23) pp:NaN4298-4298

Publication Date(Web):2008/10/15

DOI:10.1039/B814014F

The cationic Rh–SEGPHOS complex catalyzed an intermolecular [2 + 2 + 2] cycloaddition of enynes, possessing an ortho-substituted aryl group on their alkyne terminus, with acetylenedicarboxylates. Bicyclic cyclohexa-1,3-dienes with both central and axial chiralities were obtained in extremely highly diastereo- and enantioselective manner.

The first asymmetric Sonogashira coupling for the enantioselective generation of planar chirality in paracyclophanes

Co-reporter:Kazumasa Kanda, Tamami Koike, Kohei Endo and Takanori Shibata

Chemical Communications 2009(Issue 14) pp:NaN1872-1872

Publication Date(Web):2009/02/24

DOI:10.1039/B818904H

The double Sonogashira coupling of diiodoparacyclophanes with alkynes proceeded to give planarly chiral dialkynylparacyclophanes; a chiral Pd catalyst, which was prepared in situ from PdCl2(CH3CN)2 and Taniaphos, realized the first asymmetric Sonogashira coupling with up to ca. 80% ee.

Rh-catalyzed intermolecular and enantioselective [4 + 2] cycloaddition of 1,3-dienes with dimethyl acetylenedicarboxylate

Co-reporter:Takanori Shibata, Daisuke Fujiwara and Kohei Endo

Organic & Biomolecular Chemistry 2008 - vol. 6(Issue 3) pp:NaN467-467

Publication Date(Web):2007/12/11

DOI:10.1039/B717914F

A Rh-BINAP complex catalyzed an intermolecular and enantioselective [4 + 2] cycloaddition of 1-monosubstituted, 1,1- or 1,2-disubstituted buta-1,3-dienes with dimethyl acetylenedicarboxylate to give chiral cyclohexa-1,4-dienes.

Ru-catalyzed β-selective and enantioselective addition of amines to styrenes initiated by direct arene-exchange

Co-reporter:Maiko Otsuka, Hiroya Yokoyama, Kohei Endo and Takanori Shibata

Organic & Biomolecular Chemistry 2012 - vol. 10(Issue 19) pp:NaN3818-3818

Publication Date(Web):2012/03/27

DOI:10.1039/C2OB25457C

A catalytic β-selective addition of amines to styrenes proceeded in the presence of cationic Ru complexes combined with diphosphine ligands. In the reaction of α-methylstyrene, an enantioselective addition was achieved by using xylylBINAP.

Highly enantioselective synthesis of silahelicenes using Ir-catalyzed [2+2+2] cycloaddition

Co-reporter:Takanori Shibata, Toshifumi Uchiyama, Yusuke Yoshinami, Satoshi Takayasu, Kyoji Tsuchikama and Kohei Endo

Chemical Communications 2012 - vol. 48(Issue 9) pp:NaN1313-1313

Publication Date(Web):2011/11/21

DOI:10.1039/C1CC16762F

Silahelicenes, which contain two silole moieties in a helically chiral structure, were synthesized by a chiral Ir-catalyzed intermolecular [2+2+2] cycloaddition of tetraynes with diynes along with a Ni-mediated intramolecular [2+2+2] cycloaddition. The photophysical properties of the obtained highly enantiomerically enriched silahelicenes (up to 93% ee) were also measured.

Catalytic SNAr reaction of non-activated fluoroarenes with amines via Ru η6-arene complexes

Co-reporter:Maiko Otsuka, Kohei Endo and Takanori Shibata

Chemical Communications 2010 - vol. 46(Issue 2) pp:NaN338-338

Publication Date(Web):2009/11/26

DOI:10.1039/B919413D

Ru-catalyzed SNAr reaction of non-activated fluoroarenes with secondary amines proceeded through η6-arene complexes to give aminated products in up to 79% yield.

Enantioselective synthesis of planar-chiral benzosiloloferrocenes by Rh-catalyzed intramolecular C–H silylation

Co-reporter:Takanori Shibata, Tsubasa Shizuno and Tomoya Sasaki

Chemical Communications 2015 - vol. 51(Issue 37) pp:NaN7804-7804

Publication Date(Web):2015/02/06

DOI:10.1039/C5CC00723B

The first synthesis of planar-chiral benzosiloloferrocenes was achieved by the intramolecular reaction of 2-(dimethylhydrosilyl)arylferrocenes. The enantioselective cross dehydrogenative coupling of an sp2 C–H bond of ferrocene with a Si–H bond proceeded efficiently with the use of a Rh-chiral diene catalyst.

Enantioselective sp3 C–H alkylation of γ-butyrolactam by a chiral Ir(I) catalyst for the synthesis of 4-substituted γ-amino acids

Co-reporter:Yu-ki Tahara, Masamichi Michino, Mamoru Ito, Kyalo Stephen Kanyiva and Takanori Shibata

Chemical Communications 2015 - vol. 51(Issue 93) pp:NaN16663-16663

Publication Date(Web):2015/09/21

DOI:10.1039/C5CC07102J

Ir-catalyzed sp3 C–H alkylation of γ-butyrolactam with alkenes was used for the highly enantioselective synthesis of 5-substituted γ-lactams, which were readily converted into chiral 4-substituted γ-amino acids. A broad scope of alkenes was amenable as coupling partners, and the alkylated product using acrylate could be transformed into the key intermediate of pyrrolam A synthesis.

Cationic iridium-catalyzed C–H alkylation of 2-substituted pyridine N-oxides with acrylates

Co-reporter:Takanori Shibata and Hideaki Takano

Inorganic Chemistry Frontiers 2015 - vol. 2(Issue 4) pp:NaN387-387

Publication Date(Web):2015/02/11

DOI:10.1039/C4QO00355A

The reaction of 2-arylmethyl-, 2-aryl-, and 2-alkyl substituted pyridine N-oxides with acrylates proceeded in the presence of a cationic Ir-rac-BINAP catalyst under heating conditions. Various 2,6-disubstituted pyridine N-oxides were obtained by C–H alkylation at the C6-position.