171364-79-7Relevant articles and documents
Stoichiometric and Catalytic Aryl?Cl Activation and Borylation using NHC-stabilized Nickel(0) Complexes
Kuehn, Laura,Jammal, Dominik G.,Lubitz, Katharina,Marder, Todd B.,Radius, Udo
, p. 9514 - 9521 (2019)
NHC-nickel (NHC=N-heterocyclic carbene) complexes are efficient catalysts for the C?Cl bond borylation of aryl chlorides using NaOAc as a base and B2pin2 (pin=pinacolato) as the boron source. The catalysts [Ni2(ICy)4(μ-(η2:η2)-COD)] (1, ICy=1,3-dicyclohexylimidazolin-2-ylidene; COD=1,5-cyclooctadiene), [Ni(ICy)2(η2-C2H4)] (2), and [Ni(ICy)2(η2-COE)] (3, COE=cyclooctene) compare well with other nickel catalysts reported previously for aryl-chloride borylation with the advantage that no further ligands had to be added to the reaction. Borylation also proceeded with B2neop2 (neop=neopentylglycolato) as the boron source. Stoichiometric oxidative addition of different aryl chlorides to complex 1 was highly selective affording trans-[Ni(ICy)2(Cl)(Ar)] (Ar=4-(F3C)C6H4, 11; 4-(MeO)C6H4, 12; C6H5, 13; 3,5-F2C6H3, 14).
Direct C?H Borylation of Arenes Catalyzed by Saturated Hydride-Boryl-Iridium-POP Complexes: Kinetic Analysis of the Elemental Steps
Esteruelas, Miguel A.,Martínez, Antonio,Oliván, Montserrat,O?ate, Enrique
, p. 12632 - 12644 (2020)
The saturated trihydride IrH3{κ3-P,O,P-[xant(PiPr2)2]} (1; xant(PiPr2)2=9,9-dimethyl-4,5-bis(diisopropylphosphino)xanthene) activates the B?H bond of two molecules of pinacolborane (HBpin) to give H2, the hydride-boryl derivatives IrH2(Bpin){κ3-P,O,P-[xant(PiPr2)2]} (2) and IrH(Bpin)2{κ3-P,O,P-[xant(PiPr2)2]} (3) in a sequential manner. Complex 3 activates a C?H bond of two molecules of benzene to form PhBpin and regenerates 2 and 1, also in a sequential manner. Thus, complexes 1, 2, and 3 define two cycles for the catalytic direct C?H borylation of arenes with HBpin, which have dihydride 2 as a common intermediate. C?H bond activation of the arenes is the rate-determining step of both cycles, as the C?H oxidative addition to 3 is faster than to 2. The results from a kinetic study of the reactions of 1 and 2 with HBpin support a cooperative function of the hydride ligands in the B?H bond activation. The addition of the boron atom of the borane to a hydride facilitates the coordination of the B?H bond through the formation of κ1- and κ2-dihydrideborate intermediates.
Synthesis, structure, and reactivity of anionic sp2-sp3 diboron compounds: Readily accessible boryl nucleophiles
Pietsch, Sabrina,Neeve, Emily C.,Apperley, David C.,Bertermann, Rüdiger,Mo, Fanyang,Qiu, Di,Cheung, Man Sing,Dang, Li,Wang, Jianbo,Radius, Udo,Lin, Zhenyang,Kleeberg, Christian,Marder, Todd B.
, p. 7082 - 7099 (2015)
Lewis base adducts of tetra-alkoxy diboron compounds, in particular bis(pinacolato)diboron (B2pin2), have been proposed as the active source of nucleophilic boryl species in metal-free borylation reactions. We report the isolation and detailed structural characterization (by solid-state and solution NMR spectroscopy and X-ray crystallography) of a series of anionic adducts of B2pin2 with hard Lewis bases, such as alkoxides and fluoride. The study was extended to alternative Lewis bases, such as acetate, and other diboron reagents. The B(sp2)-B(sp3) adducts exhibit two distinct boron environments in the solid-state and solution NMR spectra, except for [(4-tBuC6H4O)B2pin2]-, which shows rapid site exchange in solution. DFT calculations were performed to analyze the stability of the adducts with respect to dissociation. Stoichiometric reaction of the isolated adducts with two representative series of organic electrophiles - namely, aryl halides and diazonium salts - demonstrate the relative reactivities of the anionic diboron compounds as nucleophilic boryl anion sources.
Controllable factors of supported IR complex catalysis for aromatic C?H borylation
Chun, Wang-Jae,Maeda, Kyogo,Manaka, Yuichi,Motokura, Ken,Nakajima, Kiyotaka,Satter, Shazia Sharmin,Uemura, Yohei
, p. 14552 - 14559 (2020)
We have developed a catalyst in which an Ir complex and organic functionalities are coimmobilized on the silica surface. The catalytic activity for aromatic C?H borylation was significantly affected by (i) the linker length of the Ir?bipyridine complex, (ii) the coimmobilized organic functionality, and (iii) the substituents on the aromatic substrate compounds. The fine-tuned supported catalyst showed higher activity than the homogeneous Ir?bipyridine complex when using a specific substrate such as benzonitrile. We elucidated this property by conducting solid-state NMR, FT-IR, XAFS, and in situ FT-IR analysis.
Aromatic C-H borylation catalyzed by hydrotris(pyrazolyl)borate complexes of rhodium and iridium
Murata, Miki,Odajima, Hiroki,Watanabe, Shinji,Masuda, Yuzuru
, p. 1980 - 1982 (2006)
Dehydrogenative coupling of 4,4,5,5-tetramethyl-1,3,2-dioxaborolane (pinacolborane) with arenes occurred in good yield in the presence of a catalytic amount of [Rh(TpMe2)-(cod)] (TpMe2 = hydrotris(3,5-dimethylpyrazolyl)borate, cod = 1,5-cyclooctadiene), [Ir(Tp)(cod)] (Tp = hydrotris-(pyrazolyl)borate), and related (pyrazolyl)borate complexes. The catalytic activity was strongly affected by substituents on the pyrazolyl rings.
Chemoselective Rhodium-Catalyzed Borylation of Bromoiodoarenes under Mild Conditions
Varni, Anthony J.,Bautista, Michael V.,Noonan, Kevin J.T.
, p. 6770 - 6777 (2020)
A chemoselective rhodium-catalyzed borylation has been developed for the preparation of aryl boronate esters. The reaction proceeds under mild conditions with excellent selectivity for C-I bonds in bromoiodoarenes and exhibits broad functional group tolerance. This procedure can act as a complementary approach toward bifunctional arenes along with other metal-catalyzed borylations. Additionally, the reaction's utility in the preparation of monomers for metal-catalyzed cross-coupling polymerization is demonstrated.
Ruthenium-catalysed dehydrogenative C-H borylation of arenes with pinacolborane
Murata, Miki,Ueda, Yosuke,Hyogo, Mayu,Kohari, Yoshihito,Namikoshi, Takeshi,Watanabe, Shinji
, p. 393 - 396 (2016)
A ruthenium complex prepared in situ from [RuCl2(p-cymene)]2 and TpMe2K[TpMe2 = hydrotris(3,5-dimethylpyrazolyl)borate] is efficient for aromatic C-H borylation with pinacolborane (4,4,5,5-tetramethyl-1,3,2-dioxaborolane). Arenes were borylated at more electron-rich positions. DFT calculations and kinetic isotope effect experiments suggest that the catalytic cycle should involve an electrophilic aromatic substitution with a borenium cation.
Electrogenerated Chemiluminescent Chemodosimeter Based on a Cyclometalated Iridium(III) Complex for Sensitive Detection of Thiophenol
Kim, Kyoung-Rok,Kim, Hoon Jun,Hong, Jong-In
, p. 1353 - 1359 (2019)
Thiophenol is the simplest aromatic thiol that is utilized for various applications in industry and agriculture. However, it should be used with care because thiophenol is readily absorbed into the human body by inhalation and ingestion, which leads to serious internal injuries. Thus, there is an urgent need for real-time and accurate monitoring of thiophenol. Despite remarkable advantages of electrogenerated chemiluminescence (ECL) analysis, ECL thiophenol probes have never been reported. Herein, a new strategy for the rapid detection of thiophenol by use of an ECL turn-on chemodosimeter based on a cyclometalated Ir(III) complex is described. This analytical system showed superior sensitivity [limit of detection (LOD) value, 3.8 nM] in comparison to the conventional fluorescence method. In addition, our system exhibited remarkable selectivity and reaction rate toward thiophenol over other analytes. Moreover, it was successfully applied to quantify thiophenol in real water samples, providing a new proof-of-concept for field monitoring based on ECL.
B-H bond cleavage via metal-ligand cooperation by dearomatized ruthenium pincer complexes
Anaby, Aviel,Butschke, Burkhard,Ben-David, Yehoshoa,Shimon, Linda J. W.,Leitus, Gregory,Feller, Moran,Milstein, David
, p. 3716 - 3726 (2014)
Organic derivatives of boronic acid are widely used reagents useful in various synthetic applications. A fundamental understanding and the exploration of new reaction pathways of boronic reagents with organometallic systems hold promise for useful advancement in chemical catalysis. Herein we present the reactions of simple boranes with dearomatized ruthenium pincer complexes based on PNP (2,6-bis(di-tert-butylphosphinomethyl)pyridine) or PNN (2-(di-tert-butylphosphinomethyl)-6-(diethylaminomethyl)pyridine) ligands. NMR studies revealed dehydrogenative addition of the borane B-H bond across the metal center and the ligand. Remarkably, new complexes were observed, which contain the boryl moiety at the benzylic carbon of the pincer ligand arm. X-ray crystal structures of new dearomatized boryl pincer complexes were obtained, and DFT calculations revealed mechanistic details of the adduct formation process through a dehydrogenative pathway. In addition, catalytic aryl-boron coupling reactions were explored. The new boryl pincer systems may possibly be useful in future postmodification techniques for ruthenium pincer complexes, as well as in catalytic B-B and B-C coupling reactions.
Sterically directed functionalization of aromatic C-H bonds: Selective borylation ortho to cyano groups in arenes and heterocycles
Chotana, Ghayoor A.,Rak, Michael A.,Smith, Milton R.
, p. 10539 - 10544 (2005)
Ir-catalyzed borylations of 4-substituted benzonitriles are described. In contrast to electrophilic aromatic substitutions and directed ortho metalations, C-H activation/borylation enables functionalization at the 2-position, adjacent to the cyano group, when the 4-subsitutent is larger than cyano. When an excess of borane reagent is used, diborylation can be achieved with a single regioisomer being formed in certain cases. Extension of sterically directed borylation to cyano-substituted, five- and six-membered ring heterocycles is also reported.
