- Reactions of pentaborane(11) with ethers
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Reactions of pentaborane(11) (B5H11) with ethers were studied at low temperatures by means of 11B NMR spectroscopy. The reactions of B5H11 with dimethyl and diethyl thioethers give the symmetrical cleavage products R2S·BH3 and R2S·B4H8. Species that are produced in the reaction system of B5H11 and oxoethers are very dependent upon the base strength of the ether. Strongly basic tetrahydrofuran can effect the unsymmetrical cleavage of B5H11 to produce H2B(THF)2+B4H9 -. Evidence for the formation of this cleavage product is based on the NMR spectral evidence and on the observed reaction products produced in the reaction of HCl with the B5H11-THF system. A second species is observable in the THF-B5H11 system which is more predominant at higher temperatures. This species is assigned as the simple adduct B5H11·THF. Moderately basic ethers like dimethyl and diethyl ethers produce only one observable species which is considered to be B5H11·OR2. Weakly basic diisopropyl ether does not react with B5H11. No direct evidence for the symmetrical cleavage of B5H11 by oxoethers has been observed. The similarities and differences between these reactions and analogous B4H10 reactions are discussed.
- Kodama, Goji,Saturnino, Dennis J.
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- Coordination Chemistry of Borane in Solution: Application to a STING Agonist
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Equilibrium constants were determined for ligand exchange reactions of borane complexes with various oxygen, sulfur, nitrogen, and phosphorus nucleophiles in solution, and a binding affinity scale was built spanning a range of 12 orders of magnitude. While the Keq are minimally dependent on the solvent, the rate of ligand exchange varies significantly. The fastest and slowest rates were observed in THF and CDCl3, respectively. Moreover, the ligand exchange rate differs in a very broad range depending on stability of the starting complex. Binding of BH3 was found to be much more sensitive to steric factors than protonation. Comparing nitrogen bases having equal steric properties, a linear correlation of BH3 binding affinity vs. Br?nsted acidity was found. This correlation can be used to quickly estimate the BH3 binding affinity of a substrate if pKa is known. Kinetic studies suggest the ligand exchange to occur as a bimolecular SN2 reaction unless other nucleophilic species were present in the reaction mixture.
- Lemaire, Sébastien,Zhdanko, Alexander,van der Worp, Boris A.
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- Simultaneous expansion of 9,10 boron-doped anthracene in longitudinal and lateral directions
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Doubly boron-doped anthracenes and pentacenes have been longitudinally and laterally expanded through annulation of thiophene or benzene rings. The obtained series of closely related compounds allowed an assessment of key structure-property relationships with a focus on optoelectronic characteristics. Most of the products are benchtop-stable blue emitters and capable of accepting two electrons in a reversible manner. The syntheses involved late-stage modifications through photocyclization or stepwise oxidative C-C coupling (DDQ/BF3·Et2O) as well as cyclocondensation of ortho-disilylated or -diborylated aryl building blocks.
- John, Alexandra,Kirschner, Sven,Fengel, Melina K.,Bolte, Michael,Lerner, Hans-Wolfram,Wagner, Matthias
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supporting information
p. 1871 - 1877
(2019/02/28)
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- Stabilizer-containing borane reagent combination solution, and preparation method and use thereof
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The invention provides a stabilizer-containing borane reagent combination solution. The borane reagent combination solution comprises a borane-dimethyl sulfide complex, tetrahydrofuran and a stabilizer, wherein the concentration of the borane-dimethyl sulfide complex in tetrahydrofuran is 1-10 mol/L, and a molar ratio of the borane-dimethyl sulfide complex to the stabilizer is 100:1 to 1000:1. Thecombination solution has the advantages of high concentration, good thermal stability, realization of high-efficiency utilization of a reaction container, and saving of the tetrahydrofuran reagent toreduce the cost; and the combination solution achieves a good reaction enantioselectivity and a high enantiomeric excess value (% ee) of a product when applied to Corey asymmetric reduction.
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Paragraph 0035-0036
(2018/06/04)
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- A METHOD TO PRODUCE BORANE COMPLEXES, REAGENTS FOR THE SAME, AND USE OF THE REAGENTS
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The present invention relates to a diborane-free method for producing borane complexes, such as borane dimethyl sulfide. The method includes reacting boron trifluoride and a Lewis base with a certain tertiary amines, such as 1,2,2,6,6- pentamethylpiperidineunder hydrogen atmosphere. The invention relates also to recovery of side products produced, and reagents for use in preparation of borane complexes.
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Page/Page column 19
(2017/11/06)
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- Reaction of dimethyl sulfide-triborane(7) with dimethyl sulfide. A formation reaction of pentaborane(9)
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The triborane(7) adduct of dimethyl sulfide was isolated as a liquid at room temperature. The adduct reacted with additional dimethyl sulfide to give pentaborane(9) and dimethyl sulfide-borane(3). This conversion of triborane(7) to pentaborane(9) was interpreted in terms of borane framework expansion involving diborane(4) adducts that had been established in this laboratory.
- Ishii, Minoru,Kodama, Goji
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p. 817 - 820
(2008/10/08)
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- ORGANOBORANES. XXV. HYDRIDATION OF DIALKYLHALOBORANES. NEW PRACTICAL SYNTHESES OF DIALKYLBORANES UNDER MILD CONDITIONS
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Practical methods for the synthesis of dialkylboranes (R2BH) via the hydridation of dialkylhaloboranes (R2BX) have been developed.Convenient methods available for the preparation of R2BX via the hydroboration of alkenes with monohaloborane complexes (H2BX*SMe2) make this approach valuable for the preparation of various dialkylboranes, R2BH, many of which are not available by direct hydroboration of alkenes with borane itself.The suitability of various hydriding agents, such as borane derivatives, complex metal hydrides, and alkoxy metal hydrides, for the hydridationof R2BX was examined, utilizing B-halo-9-borabicyclononane as a representative dialkylhaloborane.In this case, the unusual stability of the resulting dialkylborane, 9-BBN, permits direct estimation of the reaction products by 11B NMR spectroscopy.The generality of the procedure has been demonstrated.
- Brown, Herbert C.,Kulkarni, Surendra U.
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p. 299 - 308
(2007/10/02)
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- Nuclear magnetic resonance spectra of B2H7-. Preparation and properties of [P(C6H5)3CH3+][B 2H7-]
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The salt [P(C6H5)3CH3+][B 2H7-] was isolated from the reaction of B2H6 with [P(C6H5)3CH3+][BH 4-]. Variable-temperature pmr spectra (-80 to +110°) of [P(C6H5)3CH3+][B 2H7-] demonstrate intramolecular exchange of bridge and terminal hydrogens at temperatures above 50°. Spin coupling of bridge and terminal hydrogens was observed near -35°. The compound is stable in a closed system to nearly 100° but rapidly loses diborane at 100° under dynamic vacuum. The B2H7- ion is apparently unaffected by tetrahydrofuran. With (CH3)2S the reaction (CH3)2S + B2H7- ?CH2Cl2 (CH3)2SBH3 + BH4- is observed. The equilibrium constant as a function of temperature was determined from boron-11 nmr spectra. With N(CH3)3 the corresponding reaction is apparently complete.
- Hertz,Johnson II,Shore
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p. 1875 - 1877
(2008/10/08)
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