7519-94-0Relevant articles and documents
4-bromophenylboronate derivatives of ring and cage borosilicates
Avent, Anthony G.,Lawrence, Simon E.,Meehan, Margaret M.,Russell, Tom G.,Spalding, Trevor R.
, p. 1051 - 1060 (2002)
The reactions between equimolecular amounts of 4-bromophenylboronic acid and di-tertbutylsilanediol or tert-butylsilanetriol in toluene solutions at reflux temperatures afforded the borosilicate ring compound [(4-BrC6H4B)O2/sub
Copper-Catalyzed Asymmetric Arylation of N-Heteroaryl Aldimines: Elementary Step of a 1,4-Insertion
Wu, Chunlin,Qin, Xurong,Moeljadi, Adhitya Mangala Putra,Hirao, Hajime,Zhou, Jianrong Steve
supporting information, p. 2705 - 2709 (2019/02/06)
Copper complexes of monodentate phosphoramidites efficiently promote asymmetric arylation of N-azaaryl aldimines with arylboroxines. DFT calculations and experiments support an elementary step of 1,4-insertion in the reaction pathway, a step in which an aryl-copper species adds directly across four atoms of C=N?C=N in the N-azaaryl aldimines.
Kinetics and Mechanism of the Palladium-Catalyzed Oxidative Arylating Carbocyclization of Allenynes
Bartholomeyzik, Teresa,Pendrill, Robert,Lihammar, Richard,Jiang, Tuo,Widmalm, G?ran,B?ckvall, Jan-E.
supporting information, p. 298 - 309 (2018/01/17)
Pd-catalyzed C-C bond-forming reactions under oxidative conditions constitute a class of important and widely used synthetic protocols. This Article describes a mechanistic investigation of the arylating carbocyclization of allenynes using boronic acids and focuses on the correlation between reaction conditions and product selectivity. Isotope effects confirm that either allenic or propargylic C-H activation occurs directly after substrate binding. With an excess of H2O, a triene product is selectively formed via allenic C-H activation. The latter C-H activation was found to be turnover-limiting and the reaction zeroth order in reactants as well as the oxidant. A dominant feature is continuous catalyst activation, which was shown to occur even in the absence of substrate. Smaller amounts of H2O lead to mixtures of triene and vinylallene products, where the latter is formed via propargylic C-H activation. The formation of triene occurs only in the presence of ArB(OH)2. Vinylallene, on the other hand, was shown to be formed by consumption of (ArBO)3 as a first-order reactant. Conditions with sub-stoichiometric BF3·OEt2 gave selectively the vinylallene product, and the reaction is first order in PhB(OH)2. Both C-H activation and transmetalation influence the reaction rate. However, with electron-deficient ArB(OH)2, C-H activation is turnover-limiting. It was difficult to establish the order of transmetalation vs C-H activation with certainty, but the results suggest that BF3·OEt2 promotes an early transmetalation. The catalytically active species were found to be dependent on the reaction conditions, and H2O is a crucial parameter in the control of selectivity.
A process for preparing aldehyde group benzene boric acid
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Paragraph 0018; 0019; 0020, (2017/07/04)
The invention discloses a method for preparing formyl phenylboronic acid, which comprises the following steps: heating halogenated phenylboronic acid in toluene or heptane under reflux for dewatering to form a tripolymer, mixing the tripolymer with dimethylformamide, dropwisely adding n-butyllithium at low temperature to react by a one-pot process, hydrolyzing with hydrochloric acid, and recrystallizing to obtain the formyl phenylboronic acid. The method is simple to operate, avoids the process of separating the intermediate after formyl protection in the conventional technique, has high universality, can obtain favorable yield for ortho-, meta- and para- formyl phenylboronic acids, and is beneficial to scale-up production.
Unveiling the role of boroxines in metal-free carbon-carbon homologations using diazo compounds and boronic acids
Bomio, Claudio,Kabeshov, Mikhail A.,Lit, Arthur R.,Lau, Shing-Hing,Ehlert, Janna,Battilocchio, Claudio,Ley, Steven V.
, p. 6071 - 6075 (2017/08/29)
By means of computational and experimental mechanistic studies the fundamental role of boroxines in the reaction between diazo compounds and boronic acids was elucidated. Consequently, a selective metal-free carbon-carbon homologation of aryl and vinyl boroxines using TMSCHN2, giving access to TMS-pinacol boronic ester products, was developed.
A process for preparing carboxyl boric acid
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Paragraph 0020; 0021, (2017/08/25)
The invention discloses a method for preparing carboxyl phenylboronic acid. The method comprises the following steps of starting from halogenated phenylboronic acid, heating, refluxing and dehydrating in a solvent to form a tripolymer; then forming a grignard reagent of corresponding tripolymer from tripolymer and magnesium metal or isopropyl magnesium chloride; then introducing a carbon dioxide gas at low temperature or adding dry ice for reaction; after the reaction is finished, adding hydrochloric acid, regulating till pH is equal to 2-3, and hydrolyzing; and precipitating carboxyl phenylboronic acid, filtering, and drying to obtain a pure product. The method disclosed by the invention can achieve good yield on ortho-position, meta-position and para-position carboxyl phenylboronic acid, is simple in used reagent and easy and convenient to operate and prevents the generation of a large quantity of solid wastes.
Palladium(II)-Catalyzed Enantioselective Synthesis of α-(Trifluoromethyl)arylmethylamines
Johnson, Thomas,Luo, Bo,Lautens, Mark
, p. 4923 - 4930 (2016/07/06)
We describe a method for the synthesis of α-(trifluoromethyl)arylmethylamines that consists of the palladium(II)-catalyzed addition of arylboroxines to imines derived from trifluoroacetaldehyde. Palladium acetate is used as a catalyst with electron-neutral or electron-rich arylboroxines, and it was found that addition of an ammonium or silver salt was crucial to promote the reaction of electron-poor boroxines. With (S)-t-Bu-PyOX as the chiral ligand, this method delivers a variety of α-trifluoromethylated amines in 57-91% yield and with greater than 92% ee in most cases.
Rhodium-Catalyzed Asymmetric Arylation/Defluorination of 1-(Trifluoromethyl)alkenes Forming Enantioenriched 1,1-Difluoroalkenes
Huang, Yinhua,Hayashi, Tamio
supporting information, p. 12340 - 12343 (2016/10/07)
The reaction of 1-(trifluoromethyl)alkenes (CF3CH=CHR) with arylboroxines (ArBO)3 in the presence of a chiral diene-rhodium catalyst gave high yields of chiral 1,1-difluoroalkenes (CF2=CHC?HArR) with high enantioselectivity (≥95% ee). The reaction is assumed to proceed through β-fluoride elimination of a β,β,β-trifluoroalkylrhodium intermediate that is generated by arylrhodation of the 1-(trifluoromethyl)alkene.
Oxidative coupling of aryl boron reagents with sp3-carbon nucleophiles: The enolate chan–evans–lam reaction
Moon, Patrick J.,Halperin, Heather M.,Lundgren, Rylan J.
supporting information, p. 1894 - 1898 (2016/12/03)
Reported is a versatile new oxidative method for the arylation of activated methylene species. Under mild reaction conditions (RT to 40°C), Cu(OTf)2mediates the selective coupling of functionalized aryl boron species with a variety of stabilized sp3-nucleophiles. Tertiary malonates and amido esters can be employed as substrates to generate quaternary centers. Complementing either traditional cross-coupling or SNAr protocols, the transformation is chemoselective in the presence of halogen electrophiles, including aryl bromides and iodides. Substrates bearing amide, sulfonyl, and phosphonyl groups, which are not amenable to coupling under mild Hurtley-type conditions, are suitable reaction partners.
Asymmetric Synthesis of Triarylmethanes by Rhodium-Catalyzed Enantioselective Arylation of Diarylmethylamines with Arylboroxines
Huang, Yinhua,Hayashi, Tamio
supporting information, p. 7556 - 7559 (2015/07/01)
The reaction of racemic diarylmethylamines, (Ar1Ar2CHNR2), where Ar1 is substituted with a 2-hydroxy group, with arylboroxines (Ar3BO)3 in the presence of a chiral diene-rhodium catalyst gave high yields of chiral triarylmethanes (Ar1Ar2CH?Ar3) with high enantioselectivity (up to 97% ee). The reaction is assumed to proceed through o-quinone methide intermediates which undergo Rh-catalyzed asymmetric 1,4-addition of the arylboron reagents.
