- Boron complexes of S-trityl-L-cysteine and S-tritylglutathione
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S-Trityl-L-cysteine and S-tritylglutathione have been converted to 1,3,2-oxazaborolidine-5-ones by reaction with B-methoxydi-alkylborane derivatives. The synthesis of dicyclohexyl[S-trityl-(R)-cysteinato-O,N]boron (2), diisopinocampheyl[S-trityl-(R)-cysteinato-O,N]boron (3) and 9-borabicyclo[3.3.1]non-9-yl[S-tritylglutathionato-O,N]boron (5), dicyclohexyl[S-tritylglutathionato-O,N]boron (6) and diisopinocampheyl[S-tritylglutathionato-O,N]boron (7) from S-trityl-L-cysteine and S-tritylglutathione, respectively, with potential application in boron neutron capture therapy is reported. The structure of 9-borabicyclo[3.3.1]non-9-yl[S-trityl-(R)-cysteinato-O,N]boron 1 has been determined by X-ray diffraction.
- Díaz, Sandra,González, Asensio,González De Riancho, Sandra,Rodríguez, Ana
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- Zinc-promoted reductive coupling reactions. Reaction of sodium methoxyalkenyldialkylborates(1-) with alkenylzinc chlorides or zinc chloride
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Sodium methoxyalkenyldialkylborates(1-) react with alkenylzinc chlorides or zinc chloride to provide excellent yields of symmetrical 1,3-dienes in an unprecedented reductive coupling process.
- Molander, Gary A.,Zinke, Paul W.
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- Method for Preparing Methoxyboranes and for Producing Methanol
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The present disclosure relates to a method for preparing methoxyboranes by dismutation of formic acid or at least one of the derivatives thereof or a mixture of formic acid and at least one of the derivatives thereof, in the presence of an organoborane, and optionally an organic or inorganic base.
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Paragraph 0183; 0184; 0187; 0188
(2018/12/04)
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- Metal-free disproportionation of formic acid mediated by organoboranes
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In the presence of dialkylboranes, formic acid can be converted to formaldehyde and methanol derivatives without the need for an external reductant. This reactivity, in which formates serve as the sole carbon and hydride sources, represents the first exam
- Chauvier, Clément,Thuéry, Pierre,Cantat, Thibault
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p. 5680 - 5685
(2016/09/04)
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- Poly(propylene sulfide)-borane: Convenient and versatile reagent for organic synthesis
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Poly(trimethylene sulfide)-borane adduct has been used as an efficient borane reagent in hydroboration reactions to produce various organoboranes, which have then been used without isolation in further reactions that involve single, double and triple migrations of alkyl groups. The presence of the polymer causes no problems, but there are practical advantages associated with its use, including lack of odour and easy recoverability.
- Smith, Keith,Balakit, Asim A.,El-Hiti, Gamal A.
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p. 7834 - 7839
(2012/09/22)
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- Molecular addition compounds. 15. Synthesis, hydroboration, and reduction studies of new, highly reactive tert-butyldialkylamine-borane adducts
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Two series of tert-butyldialkylamines have been prepared and examined for borane complexation. The complexing ability of each amine in the two series examined decreases in the order shown. First series: t- BuN(CH2CH2)2O 1a > t-BuNEt2 1b > t-BuNPr(n)21c > t-BuN(CH2CH2OMe)2 1d >> t-BuNBu(i)2 1e. Second series: t-BuNBu(i)Me 2a > t-BuNPr(i)Me 2b > t- BuNBu(i)Et 2c > t-BuNBu(i)Pr(n) 2d >>t-BuNPr(i)Et 2e. The reactivity of the corresponding borane adducts toward 1-octene increases in the reverse order. The following amines form highly reactive liquid borane adducts hydroborating 1-octene in tetrahydrofuran at room temperature in less than 1 h: t- BuN(CH2CH2OMe)2, t-BuNBu(i)Et, and t-BuNPr(i)Me. The limit of borane complexation among the amines examined is reached for t-BuNBu(i)2 exchanging borane neither with BMS nor with BH3-THF. Among the various borane adducts prepared, the more promising borane adducts, t-Bu(CH3OCH2CH2)2N-BH3 (7), t-BuMePr(i)N-BH3 (8), and t-BuEtBu(i)N-BH3 (9), were selected for complete hydroboration and reduction studies. Hydroboration studies with the new, highly reactive trialkylamine-borane adducts 7-9 and representative olefins, such as 1-hexene, styrene, β-pinene, cyclopentene, norbornene, cyclohexene, 2-methyl-2-butene, α-pinene, and 2,3-dimethyl-2-butene, in tetrahydrofuran, dioxane, tert-butyl methyl ether, n-pentane, and dichloromethane, at room temperature (22 ± 3°C) were carried out. The reactions are faster in dioxane, requiring 1-2 h for the hydroboration of simple, unhindered olefins to the trialkylborane stage. Moderately hindered olefins, such as cyclohexene and 2-methyl-2-butene, give the corresponding dialkylboranes rapidly, with further slow hydroboration. However, the more hindered olefins, α-pinene and 2,3-dimethyl-2-butene, give stable monoalkylboranes very rapidly, with further hydroboration proceeding relatively slowly. The hydroborations can also be carried out conveniently in other solvents, such as THF, tert-butyl methyl ether, and n-pentane. A significant rate retardation is observed in dichloromethane. Regioselectivity studies of 1-hexene and styrene using these amine-borane adducts show selectivities similar to that of BH3-THF. The rates and stoichiometry of the reaction of t-BuMePr(i)N-BH3 in tetrahydrofuran with selected organic compounds containing representative functional groups were also examined at room temperature. The reductions of esters, amides, and nitriles, which exhibit a sluggish reaction at room temperature, proceed readily under reflux conditions in tetrahydrofuran and dioxane and without solvent (at 85-90°C). The carrier amines can be recovered by simple acid-base manipulations in good yield and readily recycled to make the borane adducts.
- Brown, Herbert C.,Kanth, Josyula V. B.,Dalvi, Pramod V.,Zaidlewicz, Marek
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p. 6263 - 6274
(2007/10/03)
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- Transfer of alk-1-enyl group from boron to boron: Preparation of B-[(E)-alk-1-enyl]-9-borabicyclo[3.3.1]nonane
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Treatment of (E)-alk-1-enyldicyclohexylborane 1 with B-methoxy-9-borabicyclo[3.3.1]nonane (B-MeO-9-BBN) at 0 °C results in transfer of alk-1-enyl group from boron to boron to give B-[(E)-alk-1-enyl]-9-BBN 2 with retention of configuration.
- Hoshi, Masayuki,Shirakawa, Kazuya,Arase, Akira
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p. 1225 - 1226
(2007/10/03)
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