In the case of substituted allylboronic acids and esters, these two reagents have been employed preferentially.Boronic acids and esters are versatile intermediates which have found many applications in organic synthesis, especially in the field of stereocontrolled C-C bond formation.
Reaction of dimethyl vinylboronates with bromine furnishes the corresponding vinyl bromides with inversion of configuration, allowing the transformation of a ()- or ()-vinyl bromide into the corresponding () or () diastereoisomer.Boronic acids (with R1 = allyl, substituted allyl, allenyl, and vinyl; R2 = H; eq 3), obtained from trimethyl borate, can be easily transformed into acyclic boronates, cyclic boronates, or 1,3,2-oxazaborolidines by reaction with the appropriate aliphatic alcohol,, a chiral (e.g.
(172) The first synthesis of a borylated α-methylene-γ-butyrolactone
(46) Contrasting Steric Effects of the Ketones and Aldehydes in the Reactions of the Diisopinocampheylborinates of Methyl Ketones with Aldehydes.
Synthesis Reaction of diborane with ammonia mainly ..
The polyaromatic amine (1 mmol) was stirred withtriethylamine (3 mmol) in anhydrous dichloromethane (5 ml) at atemperature of −5 to 0°C, (1.8 mmol in 2 ml anhydrousdichloromethane) was then added dropwise. Following the addition ofIsobutyl chloroformate, the mixture was agitated for 24 h(monitored by TLC). After completion of the reaction, the mixturewas washed with a saturated solution of sodium bicarbonate, brineand water successively. The pure product was isolated after columnchromatography over silica gel (>70% yield).
Synthesis of 2-borane-1,3-dimethylimidazolin ..
The nitrated PAH (1 mmol) and indium (570 mg), 2.5ml ethanol and 2.5 ml 20% aqueous ammonium chloride solution wererefluxed vigorously for 24 h (monitored by TLC). After completionof the reaction, the mixture was filtered through a Büchner funneland the filtrate was extracted with dichloromethane (2×3 ml). Thedichloromethane layer was washed with brine and water successivelyand dried over anhydrous sodium sulfate. The pure amine wasisolated by crystallization from a dichloromethane/hexanes mixturein excellent yield (>80%).
Prior art keywords borane dimethoxy borate trimethyl hydride
Reaction of two mol equivalents of the borane adduct of PBO with α,α′-dichloro-ortho-xylene gave the bidentate derivative, o-C6H4(CH2PBO)2.2BH3, 12, and ultimately o-C6H4(CH2PBO)2, 13.
The ratio of trimethyl borate to metal ..
For example, functionalized borate (2), obtained by in situ treatment of juglone with B(OMe) and a tartaric acid derived chiral diol, has been used as dienophile in an asymmetric Diels-Alder reaction (eq 9).Finally, in the synthesis of aplasmomycin, a boron-containing antibiotic, the boron unit was introduced as the last step by the reaction of aplasmomycin with B(OMe).