- Organoboranes. 55. Improved procedure for the conversion of representative achiral and chiral alkyl-, (E)-1-alkenyl, (Z)-1-alkenyl-, and arylboronates into the corresponding organyldichloroboranes
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Diethyl alkylboronates, R*B(OEt)2, of essentially 100% enantiomeric purity, prepared by asymmetric hydroboration of readily available prochiral alkenes, were effectively converted into the corresponding chiral alkyldichloroboranes, R*BC12, by treatment with boron trichloride (1 M solution in dichloromethane) in the presence of a catalytic amount of anhydrous ferric chloride (3 mol %). This reaction is quite general, proceeds well without detectable racemization, and is applicable to essentially optically pure boronic esters of widely varied structural requirements. The reaction is also applicable to achiral boronates, such as 1-hexyl, and hindered alkyl, such as tert-butyl. It is also applicable to the conversion of (E)- and (Z)-1-hezenylboronates, representative of the 1-alkenyl derivatives, and to phenylboronates, representative of aryl derivatives. Consequently, this procedure appears to be broadly applicable to the conversion of organylboronates, RB(OR′)2, into the corresponding organyldichloroboranes, RBCl2.
- Brown, Herbert C.,Salunkhe, Ashok M.,Argade, Ankush B.
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- PROCESS FOR REDUCING THE CONTENT OF BORON COMPOUNDS IN HALOSILANE-CONTAINING COMPOSITIONS
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The content of boron compounds in a composition containing at least one halosilane is reduced by bringing the composition into contact with at least one phenylsilane and removing the at least one halosilane. The invention further relates to the use of phenylsilanes for removing boron compounds from halosilane-containing compositions.
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Paragraph 0030; 0059
(2022/01/24)
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- The preparation of pentafluorophenyldihaloboranes from pentafluorophenylmercurials C6F5HgR and BX3: the dramatic dependence of the reaction direction on the ligand R
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Abstract: In search of convenient preparations of C6F5BX2 (X = Cl, Br), reactions of C6F5HgR (R = C6F5, C6H5, C2H5, Br and Cl) with BX3 were studied. Under the action of BCl3 the order of the C–Hg bond cleavage is C6F5Hg–C6H5 > C6F5–HgC2H5 > C6F5–HgC6F5 >> C6F5–HgCl. With more reactive BBr3 the sequence is C6F5Hg–C6H5 > C6F5–HgC2H5 ~ C6F5Hg–C2H5 > C6F5–HgC6F5 ≥ C6F5–HgBr. During the study we found the simple way to alkyldibromoboranes which is presented by the preparation of C2H5BBr2 from C2H5HgBr and BBr3. It is the second example of synthesis of alkylmercury derivative in an addition to the earlier reported formation of cyclopropylmercurials from di(cyclopropyl)mercury and BX3. Graphic abstract: [Figure not available: see fulltext.].
- Bardin, Vadim V.,Adonin, Nicolay Yu.
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p. 1523 - 1531
(2019/07/22)
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- Synthesis of arylboronates by boron-induced ipso-deantimonation of triarylstibanes with boron trihalides and its application in one-pot two-step transmetallation/cross-coupling reactions
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The reaction of triarylstibanes (1) with boron trihalides (BCl3, and BBr3) afforded arylboron dihalides (2) by utilizing all the three aryl groups on the antimony. Boron intermediates (2) were transformed to arylboronates (3) in good to excellent yields by treatment with methanol and 1,3-propanediol. Further, the Pd-catalyzed reactions of 2 with organic halides such as 1-bromonaphthalene and benzoyl chloride in the presence of H2O afforded the corresponding cross-coupling products, unsymmetrical biaryls (4) and ketones (5), in moderate to good yields. The potential energy surfaces for the transmetallations of triarylstibanes (1) with BCl3 affording 2 were determined by molecular orbital calculations. The analyses of substituent effects on theoretically calculated reactivities showed the importance of the resonance effects of the ring substituents on these transmetallations.
- Yasuike, Shuji,Nakata, Kazuhide,Qin, Weiwei,Matsumura, Mio,Kakusawa, Naoki,Kurita, Jyoji
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- Synthesis of Boron-Halogenated Diborylamines and Diborylhydrazines by Cleavage of Stannazanes
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The diborylamines R'-N(BRX)2 (3; X=Cl, Br) are obtained by stannazane cleavage of distannylorganylamines R'-N(SnMe3)2 (4) with alkyldihaloboranes RBX2 in a 1:2 molar ratio. The presence of the sterically demanding substituents R and R' also causes carbon-tin bond cleavage, resulting in low yields of 3. However, carbon-tin bond cleavage can be suppressed by the use of bis(dimethylchlorostannyl)organylamines 5 as the nitrogen source for the synthesis of diborylamines. This results in almost quantitative yields of the compounds 3. Treatment of the distannylhydrazines R2N-N(SnMe3)2 (7) with RBX2 in a 1:2 molar ratio leads to the formation of N,N-bis(alkylhaloboryl)hydrazines 8 under mild conditions and in good yield. The molecular structures of 3 and 8 were determined by multinuclear magnetic resonance spectra in solution as well as by X-ray structure analysis in the case of 8d. A typical structural feature of 8d is the intramolecular BN adduct formation. Support for the constitutions of compounds 8c comes from MS fragmentation patterns as well as from IR spectra.
- Diemer, Stefan,Noeth, Heinrich,Storch, Wolfgang
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p. 1765 - 1780
(2007/10/03)
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- Activation of the BCO unit in the ketenylidene analogue (μ-H)3Os3(CO)9(μ3-BCO) by electrophiles: Syntheses of vinylidene and alkyne analogues
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The Lewis acids BX3 (X = Cl, Br), BH3, B-Cl-9-BBN, and PhBCl2 react with (μ-H)3Os3(CO)9(μ3-BCO) (I), a ketenylidene analogue, apparently through electrophilic attack at the oxygen of the unique carbonyl. Reactions of I with BX3 (X = Cl, Br) result in an exchange of B and C atom positions in the BCO unit to form a vinylidene analogue, (μ-H)3Os3(CO)9(μ3-CBX 2). Boron-10-labeling experiments indicate that this transformation occurs through an intramolecular interchange of the boron and carbon atom positions. The ketenylidene analogue (μ-H)3Os3(CO)8(PPh3)(μ 3-BCO) reacts similarly with BCl3 to produce (μ-H)3Os3(CO)8(PPh3)(μ 3-CBCl2). The nucleophiles PMe3, PPh3, and NMe3 add to the tricoordinate boron of (μ-H)3Os3-(CO)9(μ3-CBCl 2). Above -10°C the NMe3 adduct is converted to the salt [NMe3H][(μ-H)2Os3(CO)9(μ 3-CBCl2)] and the PMe3 adduct dissociates. The PPh3 adduct decomposes above 30°C. The reaction of (μ-H)3Os3(CO)9(μ3-BCO) with THF·BH3 produces (μ-H)3Os3(CO)9(μ3-BCH 2), a second type of vinylidene analogue. In this case the boron and carbon atoms do not change positions. Alkyne analogues, (μ-H)3Os3(CO)9[μ3-η 2-C(OBC8H14)B(Cl)] and (μ-H)3Os3(CO)9[μ3-η 2-C{OB(Ph)Cl}B(Cl)] are obtained from reactions of (μ-H)3Os3(CO)9(μ3-BCO) with B-Cl-9-BBN and PhBCl2. These compounds react with BCl3 to produce (μ-H)3Os3(CO)9(μ3-CBCl 2). They also react with HCl to produce (μ-H)3Os3(CO)9(μ3-CH).
- Workman, David P.,Jan, Deng-Yang,Shore, Sheldon G.
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p. 3518 - 3525
(2008/10/08)
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- Borylation of Arylsilanes, I. - A General, Easy, and Selective Access to Phenyldihaloboranes
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Upon treatment with trihaloboranes 2b-d the phenyltrimethylsilanes 1,6,8, and 10 yield the corresponding phenyldihaloboranes 3, 7, 9, and 11 with high selectivity.Benzylsilanes are not attacked.
- Kaufmann, Dieter
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p. 853 - 854
(2007/10/02)
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- Novel Organoboron-Oxygen-Halogenaluminium Compounds from Triorganoboroxins with Aluminium Trihalides
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4 mol of triorganoboroxins (RBO)3 (1) react with 6 mol of aluminium trihalides AlHal3 (2) under cleavage of 4 mol dihalogenoorganoboranes RBHal2 (3) leading in high yields to 2 mol of compounds 4 having the composition R4Al3B4Hal5O6 (MS analyses) .The structure of 4aa, 4ba, 4ca, and 4bb in solution is deduced from spectroscopic data (IR; 1H, 11B, 17O and 27Al NMR).The molecular structure of the solid (C6H5)4Al3B4Cl5O6 (4da) with two (AlOBOBO)-rings bonded through one penta-coordinated aluminium atom was determined by X-ray diffraction analysis.
- Koester, Roland,Angermund, Klaus,Serwatowski, Janusz,Sporzynski, Andrzej
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p. 1301 - 1314
(2007/10/02)
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- Darstellung von Arylhalogenboranen
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In a ligand-exchange reaction between aryltrimethylsilanes, (ArSiMe3) and halogenboranes, (BX3 or ArBX2), arylhalogenboranes (ArBX2, ArAr'BX or Ar2BX) and halogentrimethylsilane are formed.This transfer of substituted aromatic groups from a silicon to a boron atom is an efficient synthetic pathway for the preparation of the corresponding arylhalogenboranes and diarylhalogenboranes with different aryl groups.Physical properties and spectroscopical data of the new arylhalogenboranes are given.
- Haubold, Wolfgang,Herdtle, Joerg,Gollinger, Walter,Einholz, Wolfgang
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- A New Borylation Method for Alkylbenzene and Polystyrene
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The borylation of alkylbenzenes by Hal2BH (Hal = F, Cl, Br) gives H2 and a mixture of m- and p-alkyl(dihaloboryl)benzenes.In the case of bulky alkyl groups, such as isopropyl, tert-butyl, these are partially split off as R - H and RBHal2.The phenyl groups in polystyrene-divinylbenzene copolymers undergo borylation with Br2BH in a 55percent yield.
- Paetzold, Peter,Hoffmann, Juergen
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p. 3724 - 3733
(2007/10/02)
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