Masahito Murai

Find an error

Name:

Organization: Okayama University

Department: Division of Chemistry and Biotechnology, Graduate School of Natural Science and Technology

Title:

Chemicals
References

Rhenium-Catalyzed anti-Markovnikov Addition Reaction of Methanetricarboxylates to Unactivated Terminal Acetylenes

Co-reporter:Shunsuke Hori; Masahito Murai;Kazuhiko Takai

Journal of the American Chemical Society 2015 Volume 137(Issue 4) pp:1452-1457

Publication Date(Web):January 6, 2015

DOI:10.1021/ja5090755

A novel anti-Markovnikov addition reaction of methanetricarboxylates with terminal acetylenes under neutral conditions was achieved using a rhenium complex. This transformation represents a rare example of intermolecular anti-Markovnikov addition of carbon nucleophiles to unactivated terminal acetylenes. 1,3-Diesters having bulky substituents at the active methylene carbon are also applicable as substrates to provide anti-Markovnikov adducts as single regio- and stereoisomers. Preliminary mechanistic studies imply that the rhenium vinylidene species is the key intermediate in the current catalytic cycle.

Transition-Metal-Catalyzed Facile Access to 3,11-Dialkylfulminenes for Transistor Applications

Co-reporter:Masahito Murai, Hiroyuki Maekawa, Shino Hamao, Yoshihiro Kubozono, David Roy, and Kazuhiko Takai

Organic Letters 2015 Volume 17(Issue 3) pp:708-711

Publication Date(Web):January 29, 2015

DOI:10.1021/ol503723j

Novel [6]phenacenes (fulminenes) with two long alkyl chains at the axis positions were synthesized. This short synthesis comprises the following three steps: (1) ruthenium-catalyzed direct C–H bond arylation; (2) conversion of directing groups by Wittig reaction; and (3) bismuth- or gold-catalyzed cyclization of vinyl ether. Organic field-effect transistor devices fabricated with a thin film of 3,11-di(tetradecyl)fulminene exhibited typical p-channel normally-off properties.

Iridium-Catalyzed Dehydrogenative Silylation of Azulenes Based on Regioselective C–H Bond Activation

Co-reporter:Masahito Murai, Keishi Takami, Hirotaka Takeshima, and Kazuhiko Takai

Organic Letters 2015 Volume 17(Issue 7) pp:1798-1801

Publication Date(Web):March 24, 2015

DOI:10.1021/acs.orglett.5b00575

Use of an iridium catalyst allowed the efficient dehydrogenative functionalization of C–H bonds of azulenes with the production of hydrogen as the sole byproduct. The reaction occurred with excellent chemo- and regioselectivities to provide 2-silylazulenes even without any directing groups. Effective conjugation through the 2-position of the azulene ring was demonstrated by the unique stimuli-responsiveness against an acid–base reaction.

Iridium-Catalyzed Intermolecular Dehydrogenative Silylation of Polycyclic Aromatic Compounds without Directing Groups

Co-reporter:Dr. Masahito Murai;Keishi Takami ;Dr. Kazuhiko Takai

Chemistry - A European Journal 2015 Volume 21( Issue 12) pp:4566-4570

Publication Date(Web):

DOI:10.1002/chem.201406508

Abstract

This study describes the iridium-catalyzed intermolecular dehydrogenative silylation of C(sp²)H bonds of polycyclic aromatic compounds without directing groups. The reaction produced various arylsilanes through both SiH and CH bond activation, with hydrogen as the sole byproduct. Reactivity was affected by the electronic nature of the aromatic compounds, and silylation of electron-deficient and polycyclic aromatic compounds proceeded efficiently. Site-selectivity was controlled predominantly by steric factors. Therefore, the current functionalization proceeded with opposite chemo- and site-selectivity compared to that observed for general electrophilic functionalization of aromatic compounds.

Isolation and Structural Characterization of Geminal Di(iodozincio)methane Complexes Stabilized with Nitrogen Ligands

Co-reporter:Yusuke Nishida; Naoki Hosokawa; Masahito Murai;Kazuhiko Takai

Journal of the American Chemical Society 2014 Volume 137(Issue 1) pp:114-117

Publication Date(Web):December 24, 2014

DOI:10.1021/ja5114535

Treatment of gem-di(iodozincio)methane with pyridine or diamine derivatives resulted in the isolation of a storable gem-di(iodozincio)methane species. Use of the sterically bulky bipyridine ligand gave a gem-di(iodozincio)methane complex, which allowed the first X-ray structural analysis of such species. This work represents a rare example of the isolation of an organometallic reactive species in Schlenk equilibrium and thus provides new insight into the design of efficient and storable organometallic reagents. The isolated gem-di(iodozincio)methane complexes serve as effective methylene dianion synthons for olefination of carbonyl compounds.

Rhenium-Catalyzed Synthesis of 2H-1,2-Oxaphosphorin 2-Oxides via the Regio- and Stereoselective Addition Reaction of β-Keto Phosphonates with Alkynes

Co-reporter:Masahito Murai, Masahiro Nakamura, and Kazuhiko Takai

Organic Letters 2014 Volume 16(Issue 21) pp:5784-5787

Publication Date(Web):October 24, 2014

DOI:10.1021/ol502859w

Treatment of β-keto phosphonates (Horner–Wadsworth–Emmons reagents) with terminal alkynes in the presence of a rhenium catalyst gave 2H-1,2-oxaphosphorin 2-oxides with various substitution patterns. The reaction proceeds via two consecutive processes: cleavage of a carbon–carbon σ-bond of the β-keto phosphonate with insertion of the alkyne in a regio- and stereoselective manner, followed by cyclization of the resulting δ-phosphonyl α,β-unsaturated ketone yielding the 2H-1,2-oxaphosphorin 2-oxide. Horner–Wadsworth–Emmons reagents were found to add to nonpolar unsaturated compounds under neutral conditions.

Bismuth(III)-Catalyzed Dehydrative Etherification and Thioetherification of Phenolic Hydroxy Groups

Co-reporter:Masahito Murai, Kazuki Origuchi, and Kazuhiko Takai

Organic Letters 2014 Volume 16(Issue 14) pp:3828-3831

Publication Date(Web):July 9, 2014

DOI:10.1021/ol501744g

Use of a bismuth catalyst allowed efficient dehydrative substitution of phenolic hydroxy groups with alcohols and thiols to form C–O and C–S bonds. The reaction required equimolar amounts of two readily available substrates that generated H2O as the only byproduct. The relatively mild reaction conditions were compatible with the functional groups selected, and provided excellent chemoselectivity.

Bismuth-Catalyzed Synthesis of Polycyclic Aromatic Hydrocarbons (PAHs) with a Phenanthrene Backbone via Cyclization and Aromatization of 2-(2-Arylphenyl)vinyl Ethers

Co-reporter:Masahito Murai, Naoki Hosokawa, David Roy, and Kazuhiko Takai

Organic Letters 2014 Volume 16(Issue 16) pp:4134-4137

Publication Date(Web):July 30, 2014

DOI:10.1021/ol5018273

The reaction of 2-(2-arylphenyl)vinyl ethers in the presence of a catalytic amount of bismuth(III) triflate gave substituted phenanthrenes in excellent yields under mild reaction conditions. The reaction was also applied to the construction of other polycyclic aromatic hydrocarbons (PAHs), such as chrysene, helicene, and pyrene having a phenanthrene backbone, via regioselective cyclization. This method has the advantages of easy availability of the cyclization precursors, operational simplicity, and high reaction efficiency.

Rhodium-Catalyzed Dehydrogenative Germylation of C–H Bonds: New Entry to Unsymmetrically Functionalized 9-Germafluorenes

Co-reporter:Masahito Murai, Koji Matsumoto, Ryo Okada, and Kazuhiko Takai

Organic Letters 2014 Volume 16(Issue 24) pp:6492-6495

Publication Date(Web):December 10, 2014

DOI:10.1021/ol503355q

Rhodium-catalyzed dehydrogenative germylation leading to unsymmetrically functionalized 9-germafluorenes via Ge–H and C–H bond activation is described. Despite the significant achievements made in dehydrogenative functionalization of C–H bonds, only a limited number of examples with the fourth-row atom–H bonds have been reported. The current method enabled the synthesis of various 9-germafluorene derivatives, including tetracyclic as well as donor–acceptor substituted germoles, which may be useful for electronic device applications.