- An Olefinic 1,2-Boryl-Migration Enabled by Radical Addition: Construction of gem-Bis(boryl)alkanes
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A series of in situ formed alkenyl diboronate complexes from alkenyl Grignard reagents (commercially available or prepared from alkenyl bromides and Mg) with B2Pin2 (bis(pinacolato)diboron) react with diverse alkyl halides by a Ru photocatalyst to give various gem-bis(boryl)alkanes. Alkyl radicals add efficiently to the alkenyl diboronate complexes, and the adduct radical anions undergo radical-polar crossover, specifically, a 1,2-boryl-anion shift from boron to the α-carbon sp2 center. This transformation shows good functional-group compatibility and can serve as a powerful synthetic tool for late-stage functionalization in complex compounds. Measurements of the quantum yield reveal that a radical-chain mechanism is operative in which the alkenyl diboronates acts as reductive quencher for the excited state of the photocatalyst.
- Zhao, Binlin,Li, Zexian,Wu, Yixiao,Wang, Yandong,Qian, Jiasheng,Yuan, Yu,Shi, Zhuangzhi
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supporting information
p. 9448 - 9452
(2019/08/07)
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- Method for synthetizing vinyl boronic acid ester
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The invention discloses a method for synthetizing vinyl boronic acid ester. Chloroethylene is used as a raw material and subjected to a one-pot reaction with metallic magnesium and bi(disopropylamine) boron halide; after a midbody is distilled, diol and a polymerization inhibitor are added for a backflow reaction to obtain vinyl boronic acid ester, the yield is 79-86%, and the polymerization inhibitor needs to be added into the product for storage. The method is easy and convenient to implement, the midbody is not likely to be polymerized, purification is convenient, the yield is high, no ultralow temperature reaction is needed, and the method is suitable for industrial enlarged production.
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Paragraph 0018
(2016/12/12)
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- Synthesis of functionalized vinyl boronates via ruthenium-catalyzed olefin cross-metathesis and subsequent conversion to vinyl halides
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Functionalized vinyl pinacol boronates suitable for Suzuki cross-coupling reactions are synthesized using ruthenium-catalyzed olefin cross-metathesis of 1-propenyl pinacol boronate and various alkenes, including functionalized and 1,1-disubstituted alkenes. The resultant boronate cross products are stereoselectively transformed into predominantly Z-vinyl bromides and E-vinyl iodides. The vinyl bromides may be synthesized in a two-step, one-pot synthesis from a variety of olefins, resulting in a Z-selective formal vinyl bromide cross-metathesis reaction.
- Morrill, Christie,Grubbs, Robert H.
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p. 6031 - 6034
(2007/10/03)
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- σ-borane and dihydroborate complexes of ruthenium
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Room temperature reaction of the bis(dihydrogen) complex RuH2(H2)2(PCy3)2 (1) with excess pinacol borane (HBpin) generates the novel complex RuH[(μ-H)2Bpin](σ-HBpin)(PCy3)2 (2) by loss of dihydrogen. Complex 2 was characterized spectroscopically and by X-ray crystallography. It contains two pinacolborane moieties coordinated in a different fashion, one as a dihydroborate (B-H distances : 1.58(3) and 1.47(3) A) and the other as a σ-borane (B-H distance: 1.35(3) A). In addition, reaction of 1 with one equiv of HBpin yields total conversion to a new complex tentatively formulated as RuH[(μ-H)2Bpin](H2)(PCy3)2 (3) on the basis of NMR data. In the presence of excess HBpin, 3 is converted to 2. Furthermore, under an atmosphere of dihydrogen, a C7D8 solution of 2 rapidly converts to 3 and finally regenerates 1 over a much longer period. Thus, complex 3 is an intermediate in the formation of 2 from 1. In these processes the borane is eliminated as HBpin later hydrolyzed to BpinOBpin. Selective hydroboration of ethylene (3 bar) into C2H5Bpin is achieved using 1 or 2 as catalyst precursors in toluene, whereas in THF, competitive formation of the vinylborane C2H3Bpin (56% under 20 bar of C2H4) can be favored. Copyright
- Montiel-Palma, Virginia,Lumbierres, Maria,Donnadieu, Bruno,Sabo-Etienne, Slyviane,Chaudret, Bruno
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p. 5624 - 5625
(2007/10/03)
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