2016年6月22日水曜日

A Career in Catalysis: Masakatsu Shibasaki - ACS Catalysis (ACS Publications)

A Career in Catalysis: Masakatsu Shibasaki

Naoya Kumagai^*^†, Motomu Kanai^*^‡, and Hiroaki Sasai^*^§

^† Institute
of Microbial Chemistry (BIKAKEN), Tokyo, 3-14-23 Kamiosaki, Shinagawa-ku, Tokyo 141-0021, Japan

^‡ Graduate
School of Pharmaceutical Sciences, The University
of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan

^§ The
Institute of Scientific and Industrial Research (ISIR), Osaka University, 8-1 Mihogaoka, Ibaraki-shi, Osaka 567-0047, Japan

ACS Catal., 2016, 6, pp 4699–4709

DOI: 10.1021/acscatal.6b01227

Publication Date (Web): June 20, 2016

*E-mail: nkumagai@bikaken.or.jp., *E-mail: kanai@mol.f.u-tokyo.ac.jp., *E-mail: sasai@sanken.osaka-u.ac.jp.

Abstract

Professor
Masakatsu Shibasaki’s distinguished scientific accomplishments in the
field of asymmetric catalysis are compiled here with particular emphasis
on multimetallic cooperative catalysis. In 1992, he discovered
revolutionary multimetallic chiral complexes composed of a rare earth
metal, alkaline metals, and 1,1′-binaphthyl-2-binaphthols (BINOLs) that
promoted a number of enantioselective reactions in a highly efficient
and stereoselective manner. This finding resulted in chiral
multimetallic catalysts that have significantly advanced the field of
enantioselective catalysis.

Ligand-Enabled, Copper-Catalyzed Regio- and Stereoselective Synthesis of Trialkylsubstituted Alkenylboronates from Unactivated Internal Alkynes - Journal of the American Chemical Society (ACS Publications)

Ligand-Enabled, Copper-Catalyzed Regio- and Stereoselective Synthesis of Trialkylsubstituted Alkenylboronates from Unactivated Internal Alkynes - Journal of the American Chemical Society (ACS Publications)

Taisuke Itoh^†, Yohei Shimizu^†, and Motomu Kanai^*^†^‡

^† Graduate
School of Pharmaceutical Sciences, The University
of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan

^‡ Kanai
Life Science Catalysis Project, ERATO, Japan
Science Technology Agency, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan

J. Am. Chem. Soc., 2016, 138 (24), pp 7528–7531

DOI: 10.1021/jacs.6b04646

Publication Date (Web): June 07, 2016

*kanai@mol.f.u-tokyo.ac.jp

Abstract

We
report the first copper-catalyzed regio- and stereoselective
borylalkylation of dialkylsubstituted internal alkynes with
bis(pinacolato)diboron and alkyl halides. A catalytically generated
borylcopper species containing a novel π-accepting N-heterocyclic
carbene ligand chemoselectively reacted with unactivated internal
alkynes over alkyl halides. The intermediate alkenylcopper species
subsequently reacted with alkyl halides, affording the desired products.
The copper catalyst differentiated steric demands between the two
aliphatic substituents on the C≡C triple bond of the alkyne substrates
to exhibit high regioselectivity from a wide range of alkyne/alkyl
halide combinations. This method is useful for the straightforward
synthesis of trialkylsubstituted alkenylboronates, i.e., versatile
precursors for tetrasubstituted alkenes containing three or four
different alkylsubstituents, which are difficult to synthesize by other
methods.

Nickel-Catalyzed Asymmetric Kumada Cross-Coupling of Symmetric Cyclic Sulfates - Journal of the American Chemical Society (ACS Publications)

Meredith S. Eno, Alexander Lu, and James P. Morken^*

Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, Massachusetts 02467, United States

J. Am. Chem. Soc., Article ASAP

DOI: 10.1021/jacs.6b03384

Publication Date (Web): June 08, 2016

*morken@bc.edu

Abstract

Nickel-catalyzed
enantioselective cross-couplings between symmetric cyclic sulfates and
aromatic Grignard reagents are described. These reactions are effective
with a broad range of substituted cyclic sulfates and deliver products
with asymmetric tertiary carbon centers. Mechanistic experiments point
to a stereoinvertive S_N2-like oxidative addition of a nickel complex to the electrophilic substrate.

Selective Catalytic Oxidation of Unprotected Carbohydrates - ACS Catalysis (ACS Publications)

Kevin Chung and Robert M. Waymouth^*

Department of Chemistry, Stanford University, Stanford, 94305 California, United States

ACS Catal., 2016, 6, pp 4653–4659

DOI: 10.1021/acscatal.6b01501

Publication Date (Web): June 06, 2016

*E-mail: waymouth@stanford.edu.

Abstract

The
development of new strategies for the direct catalytic
functionalization of unprotected carbohydrates would be an enabling
advance for glycoscience. Herein we report that the catalytic oxidation
of unprotected carbohydrates can be carried out selectively with
[(neocuproine)Pd(OAc)]₂(OTf)₂ (1) to
generate the 3-ketoses. Catalytic aerobic oxidation can be carried out
with Pd loadings as low as 1% in the presence of phenolic additives.
Catalytic oxidation of a variety of unprotected pyranosides in
acetonitrile or acetonitrile/water with Pd catalyst 1 with either
oxygen or benzoquinone selectively generates the 3-ketoses. Minor
amounts of the 4-ketoses are formed competitively, particularly in the
case of pyranosides bearing axial substituents at C4 of the pyranoside.
Catalytic oxidations can also be carried out in trifluorethanol, but for
pyranosides bearing axial substituents at C2 or C4, selective oxidation
to the 3-ketose is accompanied by epimerization to afford the
equatorial 3-ketoses. Catalytic oxidation of unprotected hexafuranosides
or sialic acid derivatives occurs selectively at the exocyclic diol or
triol in trifluoroethanol to generate exocyclic hydroxyketones.

Palladium-Catalyzed Regioselective C–H Bond Arylations of Benzoxazoles and Benzothiazoles at the C7 Position - ACS Catalysis (ACS Publications)

Fatma Abdellaoui^†^‡, Chiraz Youssef^‡, Hamed Ben Ammar^‡, Thierry Roisnel^†, Jean-François Soulé^*^†, and Henri Doucet^*^†

^† Institut des Sciences
Chimiques de Rennes, UMR 6226 CNRS-Université de Rennes “Organométalliques:
Matériaux et Catalyse”, Campus de Beaulieu, 35042 Rennes, France

^‡ Laboratoire de
Synthèse Organique Asymétrique et Catalyse Homogène,
(UR 11ES56) Université de Monastir, Faculté des Sciences
de Monastir, Avenue de l’environnement, Monastir 5000, Tunisia

ACS Catal., 2016, 6, pp 4248–4252

DOI: 10.1021/acscatal.6b00678

Publication Date (Web): May 31, 2016

*E-mail: jean-francois.soule@univ-rennes1.fr., *E-mail: henri.doucet@univ-rennes1.fr.

Abstract

We
report herein, a very simple catalytic system for the direct arylation
of benzoxazole and benzothiazole derivatives at C7 position, namely,
phosphine-free PdCl₂ associated with PivOK in NMP at 150 °C.
(Thio)phenoxy chelation-assisted Pd-catalyzed C–H bond cleavage, from an
opened intermediate, was proposed to explain this unique
regioselectivity. This reaction allows the synthesis of
2-amino-6-arylphenols through the ring opening of the benzoxazole.

2,5-Oxyarylation of Furans: Synthesis of Spiroacetals via Palladium-Catalyzed Aerobic Oxidative Coupling of Boronic Acids with α-Hydroxyalkylfurans - Organic Letters (ACS Publications)

Jiuyi Li, Hui Peng, Furong Wang, Xiujun Wang, Huanfeng Jiang, and Biaolin Yin^*

School of Chemistry and Chemical
Engineering, South China University of Technology, Guangzhou 510641, China

Org. Lett., Article ASAP

DOI: 10.1021/acs.orglett.6b01472

Publication Date (Web): June 16, 2016

*E-mail: blyin@scut.edu.cn.

Abstract

A
protocol for the 2,5-oxyarylation of furan rings via Pd-catalyzed
aerobic oxidative coupling of boronic acids with α-hydroxyalkylfurans is
reported. This protocol provides rapid, green access to diverse
biologically interesting and synthetically useful unsaturated
spiroacetals from sustainable furan derivatives.

Ruthenium-Catalyzed Dehydrogenative β-Benzylation of 1,2,3,4-Tetrahydroquinolines with Aryl Aldehydes: Access to Functionalized Quinolines - Organic Letters (ACS Publications)

Zhenda Tan, Huanfeng Jiang, and Min Zhang^*

School of Chemistry &
Chemical Engineering, South China University
of Technology, Wushan
Road - 381, Guangzhou 510641, People’s Republic of China

Org. Lett., Article ASAP

DOI: 10.1021/acs.orglett.6b01390

Publication Date (Web): June 14, 2016

*minzhang@scut.edu.cn

Abstract

A
new benzylation protocol, enabling straightforward access to
β-benzylated quinolines, has been demonstrated. By employing readily
available [RuCl₂(p-cymene)]₂ as a catalyst and O₂
as a sole green oxidant, various 1,2,3,4-tetrahydroquinolines were
efficiently converted in combination with aryl aldehydes into desired
products in a step- and atom-economic fashion together with the
advantages of excellent functional group tolerance and chemoselectivity,
offering an important basis for the transformation of saturated N-heterocycles into functionalized N-heteroaromatics
via a dehydrogenative cross-coupling strategy. Mechanistic
investigations support that the reaction undergoes a
monodehydrogenation-triggered β-benzylation mode.

2016年6月21日火曜日

Highly mono-selective ortho-trifluoromethylation of benzamides via 8-aminoquinoline assisted Cu-promoted C–H activations - Chemical Communications (RSC Publishing)

Liang Hu,^a^b Xiang Chen,^a Qingwen Gui,^a Ze Tan*^a and Gangguo Zhu^b

Show Affiliations

Chem. Commun., 2016,52, 6845-6848

DOI: 10.1039/C6CC02412B
Received 19 Mar 2016, Accepted 23 Apr 2016
First published online 26 Apr 2016

A highly mono-selective ortho-trifluoromethylation of benzamides was achieved via Cu-promoted C–H activations. The reaction employs an 8-aminoquinoline group as the bidentate directing group and Togni reagent II as the CF₃ source. The reaction tolerated a wide variety of functional groups and various ortho-trifluoromethylated benzamides were efficiently synthesized in 36–82% yield.

Graphical abstract: Highly mono-selective ortho-trifluoromethylation of benzamides via 8-aminoquinoline assisted Cu-promoted C–H activations

Oxygen insertion into boroles as a route to 1,2-oxaborines - Chemical Communications (RSC Publishing)

Sam Yruegas,^a Dayna C. Patterson^a and Caleb D. Martin*^a

Show Affiliations

Chem. Commun., 2016,52, 6658-6661

DOI: 10.1039/C6CC02040B

Received 07 Mar 2016,
Accepted 26 Mar 2016
First published online 29 Mar 2016

The synthesis of 1,2-oxaborines is accomplished via the reaction of pentaarylboroles with N-methylmorpholine-N-oxide via
a 1,1-insertion reaction. The aromatic nature of 1,2-oxaborines was
evaluated by computing nuclear independent chemical shift (NICS) values.
Collectively, the experimental and computational studies indicate the
unsaturated central BOC₄ ring has appreciable aromatic character.

Graphical abstract: Oxygen insertion into boroles as a route to 1,2-oxaborines

The first synthesis and X-ray crystallographic analysis of an oxygen-bridged planarized triphenylborane - Chemical Communications (RSC Publishing)

The first synthesis and X-ray crystallographic analysis of an oxygen-bridged planarized triphenylborane - Chemical Communications (RSC Publishing)

Yuichi Kitamoto,*a Takatsugu Suzuki,b Yasuo Miyata,b Hiroshi Kita,c Kenji Funakid and Shuichi Oi*a
Show Affiliations
Chem. Commun., 2016,52, 7098-7101
DOI: 10.1039/C6CC02440H
Received 21 Mar 2016, Accepted 29 Apr 2016
First published online 29 Apr 2016

An oxygen-bridged
planarized triphenylborane has been successfully synthesized. X-ray
crystallographic analysis revealed that the molecule has a complete
planarized structure and the shortest C–B bonds among the triarylboranes
synthesized to date.

Graphical abstract: The first synthesis and X-ray crystallographic analysis of an oxygen-bridged planarized triphenylborane

Radical C–H arylations of (hetero)arenes catalysed by gallic acid - Chemical Communications (RSC Publishing)

Radical C–H arylations of (hetero)arenes catalysed by gallic acid - Chemical Communications (RSC Publishing)
Marcelle D. Perretti,^a Diego M. Monzón,^a Fernando P. Crisóstomo,^a Víctor S. Martín^a and Romen Carrillo*^a

Show Affiliations

Chem. Commun., 2016, Advance Article

DOI:10.1039/C5CC09911K

Received 01 Dec 2015,
Accepted 15 Jan 2016
First published online 15 Jan 2016

Gallic acid efficientlycatalyses radical arylations in water–acetone at room temperature. This
methodology proved to be versatile and scalable. Therefore, it constitutes a greener alternative to arylation. Moreover, considering that gallic acid is an abundant vegetable tannin, this work also
unleashes an alternative method for the reutilisation of bio-wastes.

Graphical abstract: Radical C–H arylations of (hetero)arenes catalysed by gallic acid

An effective host material with thermally activated delayed fluorescence formed by confined conjugation for red phosphorescent organic light-emitting diodes - Chemical Communications (RSC Publishing)

Xiang-Yang Liu,^a Feng Liang,^a Yi Yuan,^a Lin-Song Cui,^a Zuo-Quan Jiang*^a and Liang-Sheng Liao*^a

Show Affiliations

Chem. Commun., 2016, Advance Article

DOI: 10.1039/C6CC02856J
Received 06 Apr 2016, Accepted 24 May 2016
First published online 08 Jun 2016 A thermally activated delayed fluorescence material 2,6-bis(9,9-diphenylacridin-10(9H)-yl)pyrazine
was designed and synthesized. The twisted configuration made it
possesses very small singlet–triplet splitting. A red electroluminescent
device based on this new host material is able to achieve ∼26% external
quantum efficiency and relatively flat efficiency roll-off.

Graphical abstract: An effective host material with thermally activated delayed fluorescence formed by confined conjugation for red phosphorescent organic light-emitting diodes

Quinonediimines as redox-active organocatalysts for oxidative coupling of aryl- and alkenylmagnesium compounds under molecular oxygen - Chemical Communications (RSC Publishing)

Toru Amaya,*^a Riyo Suzuki^a and Toshikazu Hirao*^a

Show Affiliations

Chem. Commun., 2016,52, 7790-7793

DOI: 10.1039/C6CC03053J
Received 12 Apr 2016, Accepted 26 Apr 2016
First published online 12 May 2016

It is revealed that N,N′-diphenyl-p-benzoquinonediimine
works as a redox-active organocatalyst for the oxidative homo-coupling
of aryl- and alkenylmagnesium compounds under molecular oxygen. The
catalytic cycle was formally monitored by ¹H NMR experiments.

Graphical abstract: Quinonediimines as redox-active organocatalysts for oxidative coupling of aryl- and alkenylmagnesium compounds under molecular oxygen

2016年6月15日水曜日

Meta-Selective CAr–H Nitration of Arenes through a Ru3(CO)12-Catalyzed Ortho-Metalation Strategy - Journal of the American Chemical Society (ACS Publications)

Zhoulong Fan^†^‡, Jiabin Ni^†^‡, and Ao Zhang^*^†^‡

^† CAS Key Laboratory of Receptor Research, and Synthetic Organic &
Medicinal Chemistry Laboratory (SOMCL), Shanghai Institute of Materia
Medica (SIMM), Chinese Academy of Sciences, Shanghai 201203, China

^‡ University of Chinese Academy of Sciences, Beijing 100049, China

J. Am. Chem. Soc., Article ASAP

DOI: 10.1021/jacs.6b03402

Publication Date (Web): May 15, 2016

*aozhang@simm.ac.cn

Abstract

The first example of transition metal-catalyzed meta-selective C_Ar–H nitration of arenes is described. With the use of Ru₃(CO)₁₂ as the catalyst and Cu(NO₃)₂·3H₂O as the nitro source, a wide spectrum of arenes bearing diversified N-heterocycles
or oximido as the directing groups were nitrated with meta-selectivity
exclusively. Mechanism studies have demonstrated the formation of a new
18e-octahedral ruthenium species as a key ortho-C_Ar–H metalated intermediate, which may be responsible for the subsequent meta-selective electrophilic aromatic substitution (S_EAr).
Moreover, this approach provides a fast-track strategy for atom/step
economical synthesis of many useful pharmaceutical molecules.

2016年5月20日金曜日

Mild Photochemical Tethering of [RuCl2(η6-arene)P*] Complexes with P-Stereogenic 2-Biphenylylphosphines - Organometallics (ACS Publications)

Miquel Navarro, Diego Vidal, Pau Clavero, Arnald Grabulosa*, and Guillermo Muller

Departament de Química
Inorgànica, Universitat de Barcelona, Martí i Franquès,
1-11, E-08028, Barcelona, Spain

Organometallics, 2015, 34 (5), pp 973–994

DOI: 10.1021/acs.organomet.5b00018

Publication Date (Web): February 26, 2015

Abstract

The synthesis of enantiopure P-stereogenic diarylphosphines PArPhR (Ar = 9-phenanthryl (a), 1-naphthyl (b), and 2-biphenylyl (c)) with an aryl group at the β (3; R = −CH₂CH₂(2-naphthyl)) or γ position (2; R = −CH₂Si(Me₂)CH₂Ph)) is described. Treatment of 2a with [RuCl₂(η⁶-p-cymene)]₂ (Dim1) has led to complex [RuCl₂(η⁶-p-cymene)(κP-2a)] (4a). Attempts to displace the p-cymene substituent by the pendant aryl group of the phosphine have failed. Reaction of the ligands with [RuCl₂(η⁶-methyl benzoate)]₂ (Dim2) has furnished complexes [RuCl₂(η⁶-methyl benzoate)(κP-P*)] 6 and 7 (6a–c, P* = 2a–c; 7a–b, P* = 3a–b). The methyl benzoate of 6a and 6b has been successfully replaced by the phenyl ring of the arm of the phosphine, yielding complexes [RuCl₂(κP-η⁶-phenyl)-P*] (5a and 5b). Unexpectedly, complex 6c has led to tethered [RuCl₂(κP-η⁶-phenyl)-P(2-biphenylyl)PhR] complex (9c), where the coordinated phenyl ring belongs to the 2-biphenylyl group. Reaction of P(2-biphenylyl)PhR (R = OMe, Me, i-Pr, and Fc (ferrocenyl)) with Dim2 has given complexes [RuCl₂(η⁶-methyl benzoate)(κP-P(2-biphenylyl)PhR)] (10c–13c).
The replacement of methyl benzoate by the phenyl ring of the
2-biphenylyl of the phosphine can be performed at room temperature in
the presence of light, giving tethered complexes [RuCl₂(κP-η⁶-phenyl)-P(2-biphenylyl)PhR] (14c–17c). Phosphines bearing a substituted 2-biphenylyl group (PArPhR; d (Ar = 2-p-terphenylyl; R = OMe, Me, i-Pr), e (Ar = 2-m-terphenylyl; R = OMe, i-Pr), f (Ar = 2-(1′-naphthyl)phenyl; R = OMe, i-Pr), and g (Ar = 2-(2′-naphthyl)phenyl; R = OMe, i-Pr) have been prepared. Phosphines f
are present as a mixture of atropisomers. The corresponding Ru
complexes have been prepared and subjected to tethering. Tethered
complexes with phosphines d are single species in solution,
whereas the rest of the phosphines give diastereomeric mixtures with
little stereoselection. All complexes have been evaluated in
Ru-catalyzed hydrogen transfer of acetophenone in i-PrOH as a solvent obtaining full conversions and up to 47% ee using precursor [RuCl₂(κP-η⁶-phenyl)-P*] (26f, P* = P(2-(1′-naphthyl)phenyl)(OMe)Ph.

Chiral Nanoparticles/Lewis Acids as Cooperative Catalysts for Asymmetric 1,4-Addition of Arylboronic Acids to α,β-Unsaturated Amides

Chiral Nanoparticles/Lewis Acids as Cooperative Catalysts for Asymmetric 1,4-Addition of Arylboronic Acids to α,β-Unsaturated Amides
Dr. Tomohiro Yasukawa, Yuuki Saito, Dr. Hiroyuki Miyamura and Prof. Dr. Shū Kobayashi
Version of Record online: 19 MAY 2016 | DOI: 10.1002/anie.201601559

It can abide amides: Cooperative catalysts consisting of heterogeneous chiral Rh/Ag nanoparticles and a metal Lewis acid, Sc(OTf)₃ show high catalytic activities and outstanding enantioselectivities for asymmetric 1,4-addition reactions of arylboronic acids with α,β-unsaturated amides. The reaction is regarded as challenging owing to low reactivity of the amide substrates.

2016年5月19日木曜日

Relationship between the Bowl-Shaped Geometry of Phosphangulene and an Axial Group on the Phosphorus Atom

Masaki Yamamura* and Tatsuya Nabeshima*

10.1246/bcsj.20150288

Phosphangulene derivatives having various substituents on the phosphorus atom were synthesized. X-ray analysis and DFT calculation revealed that the bowl geometries become deep as the s-orbital character of the phosphorus orbital in the P–X bonds increases.

A Phenazaborin-Based High-Efficiency Blue Delayed Fluorescence Material

In Seob Park, Masaki Numata, Chihaya Adachi,* and Takuma Yasuda*

10.1246/bcsj.20150399

A highly efficient blue thermally activated delayed fluorescence material based on phenazaborin and spiroacridan units was developed. A blue-emitting organic light-emitting diode containing the phenazaborin derivatives exhibited a high external electroluminescence quantum efficiency of 18.2%.

The Influence of Quasiplanar Structures of Partially Oxygen-Bridged Triphenylamine Dimers on the Properties of their Bulk Films

Hidetaka Nishimura, Tatsuya Fukushima, Atsushi Wakamiya, Yasujiro Murata, and Hironori Kaji

10.1246/bcsj.20160031

Two kinds of oxygen-bridged triphenylamine dimers show characteristic charge-transporting behaviors, which are attributed to the difference in the partially retained π-stacking structures in their vapor-deposited films. OLEDs using these compounds as hole-injection layers exhibited higher external quantum efficiencies compared to a standard device.

Fast and Selective Dehydrogenative C–H/C–H Arylation Using Mechanochemistry - ACS Catalysis (ACS Publications)

Shao-Jie Lou, Yang-Jie Mao, Dan-Qian Xu^*, Jiang-Qi He, Qi Chen, and Zhen-Yuan Xu

Catalytic Hydrogenation Research
Center, State Key Laboratory Breeding Base of Green Chemistry−Synthesis
Technology, Zhejiang University of Technology, Hangzhou 310014, People’s Republic of China

ACS Catal., 2016, 6, pp 3890–3894

DOI: 10.1021/acscatal.6b00861

Publication Date (Web): May 16, 2016

*E-mail: chrc@zjut.edu.cn.

Abstract

A
fast and site-selective biaryl synthesis via dehydrogenative C–H/C–H
arylation in a ball mill was developed. In this paper, both
electron-deficient oximes and electron-rich anilides quickly and under
mild conditions provided arylation with various arenes to give the
biaryl products in high-level selectivity. Given the solventless
mechanochemical conditions, the transformation obviated the use of large
amounts of arene coupling partners as solvents and allowed utilization
of more-complicated and more-expensive arenes as coupling partners,
which may dramatically enhance the application prospect of the C–H/C–H
arylation strategy.

Manganese-Catalyzed C–H Activation - ACS Catalysis (ACS Publications)

Weiping Liu and Lutz Ackermann^*

Institut
für Organische
und Biomolekulare Chemie, Georg-August-Universität, Tammannstraße 2, 37077 Göttingen, Germany

ACS Catal., 2016, 6, pp 3743–3752

DOI: 10.1021/acscatal.6b00993

Publication Date (Web): April 27, 2016

*E-mail: lutz.ackermann@chemie.uni-goettingen.de. Fax: (+49)551-39-6777. Tel: (+49)551-39-3202.

Abstract

Manganese
is found in the active center of numerous enzymes that operate by an
outer-sphere homolytic C–H cleavage. Thus, a plethora of bioinspired
radical-based C–H functionalizations by manganese catalysis have been
devised during the past decades. In contrast, organometallic C–H
activation by means of manganese catalysis has emerged only recently as
an increasingly viable tool in organic synthesis. These
manganese(I)-catalyzed processes enabled a variety of C–H
functionalizations with ample scope, which very recently set the stage
for substitutive C–H functionalizations. The versatile manganese
catalysis largely operates by an isohypsic, thus redox-neutral, mode of
action through chelation assistance, and provided step-economical access
to structurally divers compounds of relevance to inter alia bioorganic, agrochemical, and medicinal chemistry as well as the material sciences.

Metal and Metal Oxide Nanoparticles: A Lever for C–H Functionalization - ACS Catalysis (ACS Publications)

Daniel Pla^*^† and Montserrat Gómez^*^‡

^† Laboratoire
de Chimie de Coordination, Centre National
de la Recherche Scientifique UPR 8241, 205 Route de Narbonne, F-31077 Toulouse Cedex 4, France

^‡ Laboratoire
Hétérochimie Fondamentale et Appliquée, Université de Toulouse 3 Paul Sabatier, UPS
and CNRS UMR 5069, 118
Route de Narbonne, F-31062 Toulouse Cedex 9, France

ACS Catal., 2016, 6, pp 3537–3552

DOI: 10.1021/acscatal.6b00684

Publication Date (Web): April 26, 2016

*E-mail: daniel.pla@cantab.net. Phone: +33581314123., *E-mail: gomez@chimie.ups-tlse.fr. Phone: +33561557738.

Abstract

The
past decade has seen the development of a new reactivity concept,
exploiting the ubiquity of C–H bonds. The direct activation of this bond
type brings forth a straightforward way for the derivatization of
organic molecules. Consequently, the design of metal catalyzed C–H bond
functionalization reactions has become a flourishing area in organic
synthesis. Thus, this review focuses on molecular transformation of
“unactivated” C(sp³)–H and C(sp²)–H bonds present
in feedstock and readily available hydrocarbons into valuable chemicals
by nanoparticle-leveraged C–H activation, resulting in more sustainable
approaches for industrial applications. The distinctive reactivity
properties of these nanoentities lead to remarkable reactivity
specificities depending on the type of surface sites and the structure
dynamics, directly impacting the process selectivity.

2016年5月18日水曜日

Luminescent monometallic Cu(i) triphenylphosphine complexes based on methylated 5-trifluoromethyl-3-(2′-pyridyl)-1,2,4-triazole ligands - New Journal of Chemistry (RSC Publishing)

Jing-Lin Chen,*^a^b Zong-Hao Guo,^a Yan-Sheng Luo,^a Lu Qiu,^a Li-Hua He,^a Sui-Jun Liu,^a He-Rui Wen^a and Jin-Yun Wang*^b

Show Affiliations

New J. Chem., 2016, Advance Article

DOI: 10.1039/C5NJ03529E

Received11 Dec 2015,
Accepted11 Apr 2016
First published online 11 Apr 2016

A new family of five new mononuclear Cu(I)
triphenylphosphine complexes derived from methylated
5-trifluoromethyl-3-(2′-pyridyl)-1,2,4-triazole ligands has been
synthesized and well characterized. They all show an N₂P₂
distorted tetrahedral geometry and the methylated
5-trifluoromethyl-3-(2′-pyridyl)-1,2,4-triazole ligands display the
mono-anionic η²(N1,N2) and charge-neutral η²(N1,N4) chelating coordination modes, along with the 1,2,4-triazolyl ring inversion induced by the NH ↔ N⁻ transformation. These Cu(I)
complexes are all emissive in solution and solid states at ambient
temperature, which can be well modulated by changing the methyl position
on the pyridyl ring and regulating the NH ↔ N⁻
conversion of the 1,2,4-triazolyl ring. It is also shown that the
deprotonation of 1,2,4-triazolyl-NH can markedly improve the
luminescence properties of Cu(I) complexes.

Graphical abstract: Luminescent monometallic Cu(i) triphenylphosphine complexes based on methylated 5-trifluoromethyl-3-(2′-pyridyl)-1,2,4-triazole ligands

Radical–Radical Cross-Coupling for C–S Bond Formation - Organic Letters (ACS Publications)

Zhiliang Huang^†, Dongchao Zhang^†, Xiaotian Qi^‡, Zhiyuan Yan^†, Mengfan Wang^†, Haiming Yan^|, and Aiwen Lei^*^†^|

^† College
of Chemistry and Molecular Sciences, Institute for Advanced Studies
(IAS), Wuhan University, Wuhan 430072, People’s Republic of China

^‡ School
of Chemistry and Chemical Engineering, Chongqing
University, Chongqing 400030, People’ s Republic of China

^| National
Research Center for Carbohydrate Synthesis, Jiangxi Normal University, Nanchang 330022, People’ s Republic
of China

Org. Lett., Article ASAP

DOI: 10.1021/acs.orglett.6b00764

Publication Date (Web): May 6, 2016

*E-mail: aiwenlei@whu.edu.cn.

Abstract

A
new method was demonstrated to overcome the selectivity issue of
radical–radical cross-coupling toward the synthesis of asymmetric diaryl
thioethers. The preliminary mechanism was revealed by radical-trapping
experiments, DFT calculations, and kinetics, etc., indicating that the
C–S bond formed through cross-coupling of a thiyl radical and an aryl
radical cation. Moreover, the formation of an aryl radical cation
instead of the C–H bond cleavage was determined as the rate-limiting
step.

Regiodivergent Cross-Dehydrogenative Coupling of Pyridines and Benzoxazoles: Discovery of Organic Halides as Regio-Switching Oxidants - Organic Letters (ACS Publications)

Shuya Yamada^†, Kei Murakami^†, and Kenichiro Itami^*^†^‡

^† Institute
of Transformative Bio-Molecules (WPI-ITbM) and Graduate School of
Science, Nagoya University, Chikusa, Nagoya 464-8602, Japan

^‡ JST,
ERATO, Itami Molecular Nanocarbon Project, Nagoya University, Chikusa, Nagoya 464-8602, Japan

Org. Lett., Article ASAP

DOI: 10.1021/acs.orglett.6b00932

Publication Date (Web): May 10, 2016

*E-mail: itami@chem.nagoya-u.ac.jp.

Abstract

Cross-dehydrogenative
coupling (CDC) of two unfunctionalized heteroarenes has been recognized
as an ideal transformation to synthesize privileged heterobiaryl
scaffolds. However, regioselective activation and transformation of a
specific set of two heterocyclic C–H bonds among other bonds have been
extremely challenging. Thus, discovering a new controlling element to
achieve regio-controlled and regio-divergent heterocyclic CDCs is
considered crucial. In this Letter, the unprecedented use of organic
halides as an oxidant to achieve the CDC reaction of pyridines and
benzoxazoles with palladium catalyst is described. Moreover, the
regioselectivity of the pyridine functionalization site can be
controlled by the choice of organic halides.

EtAlCl2/2,6-Disubstituted Pyridine-Mediated Carboxylation of Alkenes with Carbon Dioxide - Organic Letters (ACS Publications)

Shinya Tanaka^*, Kota Watanabe, Yuuki Tanaka, and Tetsutaro Hattori^*

Department of Biomolecular
Engineering, Graduate School of Engineering, Tohoku University, 6-6-11
Aramaki-Aoba, Aoba-ku, Sendai 980-8579, Japan

Org. Lett., Article ASAP

DOI: 10.1021/acs.orglett.6b00918

Publication Date (Web): May 17, 2016

*E-mail: tanaka@orgsynth.che.tohoku.ac.jp., *E-mail: hattori@orgsynth.che.tohoku.ac.jp.

Abstract

α-Arylalkenes and trialkyl-substituted alkenes undergo carboxylation with CO₂ in the presence of EtAlCl₂
and 2,6-dibromopyridine to afford the corresponding α,β- and/or
β,γ-unsaturated carboxylic acids. This reaction is suggested to proceed
via the electrophilic substitution of EtAlCl₂ with the aid of
the base, followed by the carbonation of the resulting ate complex.
This reaction can be applied to terminal dialkylalkenes by using a
mixture of 2,6-di-tert-butylpyridine and 2,6-dibromopyridine.

A Screening Approach for the Discovery of Mechanochromic Gold(I) Isocyanide Complexes with Crystal-to-Crystal Phase Transitions - Journal of the American Chemical Society (ACS Publications)

Tomohiro Seki^*, Yuki Takamatsu, and Hajime Ito^*

Division of Applied Chemistry
and Frontier Chemistry Center (FCC), Faculty
of Engineering, Hokkaido University, Sapporo, Hokkaido 060-8628, Japan

J. Am. Chem. Soc., 2016, 138 (19), pp 6252–6260

DOI: 10.1021/jacs.6b02409

Publication Date (Web): April 12, 2016

*seki@eng.hokudai.ac.jp, *hajito@eng.hokudai.ac.jp

ACS Editors' Choice - This is an open access article published under an ACS AuthorChoice License, which permits copying and redistribution of the article or any adaptations for non-commercial purposes.

Abstract

Mechanoinduced
phase transitions of emissive organic crystalline materials have
received much attention. Although a variety of such luminescent
mechanochromic compounds have been reported, it is challenging to
develop mechanochromic compounds with crystal-to-crystal phase
transitions in which precise structural information about molecular
arrangements can be obtained. Here, we report a screening approach to
explore mechanochromic compounds exhibiting a crystal-to-crystal phase
transition. We prepared 48 para-substituted (R¹) phenyl[para-substituted (R²) phenyl isocyanide]gold(I) complexes designated R¹–R² (six R¹ and eight R²
substituents) and then performed three-step screening experiments. The
first screening step was selection of emissive complexes under UV light,
which gave 37 emissive R¹–R²
complexes. The second screening step involved evaluation of the
mechanochromic properties by emission spectroscopy. Twenty-eight
complexes were found to be mechanochromic. The third screening step
involved preparation of single crystals, reprecipitated powders, and
ground powders of the 28 mechanochromic R¹–R²
complexes. The changes in the powder diffraction patterns of these
complexes induced by mechanical stimulation were investigated. Two
compounds exhibited a crystal-to-crystal phase transition upon
mechanical stimulation, including the previously reported H–H complex. Single crystals of the as-prepared and ground forms of the newly discovered CF₃–CN complex were obtained. Density functional theory calculations indicated that the mechanoinduced red-shifted emission of CF₃–CN is caused by formation of aurophilic interactions. Comparison of the crystal structures of CF₃–CN
with those of the other complexes suggests that the weaker
intermolecular interactions in the as-prepared form are an important
structural factor for the observed mechanoinduced crystal-to-crystal
phase transition.

Tetrahydroxydiboron-Mediated Palladium-Catalyzed Transfer Hydrogenation and Deuteriation of Alkenes and Alkynes Using Water as the Stoichiometric H or D Atom Donor - Journal of the American Chemical Society (ACS Publications)

Tetrahydroxydiboron-Mediated Palladium-Catalyzed Transfer Hydrogenation and Deuteriation of Alkenes and Alkynes Using Water as the Stoichiometric H or D Atom Donor - Journal of the American Chemical Society (ACS Publications)

Steven P. Cummings, Thanh-Ngoc Le, Gilberto E. Fernandez, Lorenzo G. Quiambao, and Benjamin J. Stokes^*

School of Natural Sciences, University
of California, Merced, 5200 North Lake Road, Merced, California 95343, United States

J. Am. Chem. Soc., 2016, 138 (19), pp 6107–6110

DOI: 10.1021/jacs.6b02132

Publication Date (Web): May 02, 2016

*bstokes2@ucmerced.edu

Abstract

There
are few examples of catalytic transfer hydrogenations of simple alkenes
and alkynes that use water as a stoichiometric H or D atom donor. We
have found that diboron reagents efficiently mediate the transfer of H
or D atoms from water directly onto unsaturated C–C bonds using a
palladium catalyst. This reaction is conducted on a broad variety of
alkenes and alkynes at ambient temperature, and boric acid is the sole
byproduct. Mechanistic experiments suggest that this reaction is made
possible by a hydrogen atom transfer from water that generates a
Pd–hydride intermediate. Importantly, complete deuterium incorporation
from stoichiometric D₂O has also been achieved.

Tri(1-adamantyl)phosphine: Expanding the Boundary of Electron-Releasing Character Available to Organophosphorus Compounds - Journal of the American Chemical Society (ACS Publications)

Liye Chen, Peng Ren, and Brad P. Carrow^*

Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States

J. Am. Chem. Soc., Article ASAP

DOI: 10.1021/jacs.6b03215

Publication Date (Web): May 10, 2016

*bcarrow@princeton.edu

Abstract

We report here the remarkable properties of PAd₃, a crystalline air-stable solid accessible through a scalable S_N1 reaction. Spectroscopic data reveal that PAd₃,
benefiting from the polarizability inherent to large hydrocarbyl
groups, exhibits unexpected electron releasing character that exceeds
other alkylphosphines and falls within a range dominated by
N-heterocyclic carbenes. Dramatic effects in catalysis are also enabled
by PAd₃ during Suzuki–Miyaura cross-coupling of
chloro(hetero)arenes (40 examples) at low Pd loading, including the
late-stage functionalization of commercial drugs. Exceptional space-time
yields are demonstrated for the syntheses of industrial precursors to
valsartan and boscalid from chloroarenes with ∼2 × 10⁴ turnovers in 10 min.

An Approach to Tetraphenylenes via Pd-Catalyzed C–H Functionalization - Organic Letters (ACS Publications)

Hang Jiang, Yu Zhang, Dushen Chen, Bo Zhou, and Yanghui Zhang^*

Department of Chemistry,
and Shanghai Key Lab of Chemical Assessment and Sustainability, Tongji University, 1239 Siping Road, Shanghai, 200092, P. R. China

Org. Lett., 2016, 18 (9), pp 2032–2035

DOI: 10.1021/acs.orglett.6b00641

Publication Date (Web): April 25, 2016

*E-mail: zhangyanghui@tongji.edu.cn.

Abstract

Tetraphenylenes
not only are theoretically and experimentally interesting but also have
potential applications in a variety of fields such as materials
science, supramolecular chemistry, and asymmetric catalysis. A facile
and efficient approach is reported for the syntheis of tetraphenylene
and its derivatives from 2-iodobiphenyls via Pd-catalyzed C–H
activation. A range of substituted tetraphenylenes can be synthesized
using this method, and the reaction can be performed on gram scale with
relatively high efficiency, demonstrating its practical utility. This
novel approach provides easy access to tetraphenylenes and should
facilitate research on the application of this type of fascinating
molecules.

Sequential Difunctionalization of 2-Iodobiphenyls by Exploiting the Reactivities of a Palladacycle and an Acyclic Arylpalladium Species - Organic Letters (ACS Publications)

Dushen Chen, Guangfa Shi, Hang Jiang, Yu Zhang, and Yanghui Zhang^*

Department of Chemistry,
and Shanghai Key Lab of Chemical Assessment and Sustainability, Tongji University, 1239 Siping Road, Shanghai, 200092, P. R. China

Org. Lett., 2016, 18 (9), pp 2130–2133

DOI: 10.1021/acs.orglett.6b00753

Publication Date (Web): April 26, 2016

*E-mail: zhangyanghui@tongji.edu.cn

Abstract

A
novel sequential difunctionalization reaction of 2-iodobiphenyl has
been developed by exploiting the distinct reactivities of a palladacycle
and an acyclic arylpalladium species. In this tandem reaction, an in
situ formed dibenzopalladacyclopentadiene reacts selectively with an
alkyl halide, after which the thus formed acyclic arylpalladium species
selectively undergoes a Heck reaction with an alkene. This work
demonstrates the strong relationship between the coordination mode of a
transition metal complex and its reactivity, which could shed light on
the mechanisms of other transition-metal-catalyzed reactions and offer
the opportunity to develop other synthetically enabling organic
transformations.

Copper(I)-Catalyzed Allylic Substitutions with a Hydride Nucleophile - Organic Letters (ACS Publications)

T. N. Thanh Nguyen, Niklas O. Thiel, Felix Pape, and Johannes F. Teichert^*

Institut für Chemie, Technische Universität Berlin, Straße des 17. Juni 115, 10623 Berlin, Germany

Org. Lett., Article ASAP

DOI: 10.1021/acs.orglett.6b00941

Publication Date (Web): May 6, 2016

*E-mail: johannes.teichert@chem.tu-berlin.de.

Abstract

An
easily accessible copper(I)/N-heterocyclic carbene (NHC) complex
enables a regioselective hydride transfer to allylic bromides, an
allylic reduction. The resulting aryl- and alkyl-substituted branched
α-olefins, which are valuable building blocks for synthesis, are
obtained in good yields and regioselectivity. A commercially available
silane, (TMSO)₂Si(Me)H, is employed as hydride source. This
protocol offers a unified alternative to the established metal-catalyzed
allylic substitutions with carbon nucleophiles, as no adaption of the
catalyst to the nature of the nucleophile is required.

N-Methyl Transfer Induced Copper-Mediated Oxidative Diamination of Alkynes - Organic Letters (ACS Publications)

Hon Eong Ho^†, Kazuaki Oniwa^†, Yoshinori Yamamoto^†^‡, and Tienan Jin^*^†

^† WPI-Advanced
Institute for Materials Research (WPI-AIMR), Tohoku University, Sendai, 980-8577, Japan

^‡ State
Key Laboratory of Fine Chemicals, Dalian
University of Technology, Dalian, 116012, China

Org. Lett., Article ASAP

DOI: 10.1021/acs.orglett.6b01067

Publication Date (Web): May 6, 2016

*E-mail: tjin@m.tohoku.ac.jp.

Abstract

A
novel intramolecular oxidative diamination of
bis(2-aminophenyl)acetylene for the synthesis of the structurally
intriguing π-conjugated polyheterocyclic scaffold,
5,10-dihydroindolo[3,2-b]indole (DHII), has been developed under Cu(hfacac)₂/O₂ oxidation systems. The structure design of bis(2-aminophenyl)acetylene bearing both N,N-dimethylamine and primary amine groups is crucial for constructing the corresponding DHII scaffold. Notably, an intermolecular N-methyl transfer from the nitrogen atom of N,N-dimethylamine
to the primary amine takes place, which is a critical step for the
successful implementation of the present annulation process.

登録: 投稿 (Atom)