It was found that the reaction of thioboronites with carbonyl compounds and ketene proceeds with the initial formation of vinyloxyboranes (VII). The boranes were found to be important intermediates for the formation of β-hydroxythiolesters by the reaction with various carbonyl compounds. Vinyloxyborane derivatives can be alternatively prepared by the reactions of trialkylboranes and α-diazocarbonyl
Highly stereoselective synthesis of chiral aldol polymers using repeated asymmetric Mukaiyama aldol reaction
作者:Shinichi Itsuno、Kenichi Komura
DOI:10.1016/s0040-4020(02)00973-0
日期:2002.10
Asymmetricaldol polymerization of bis(triethylsilyl enol ether) and dialdehyde was performed in the presence of chiral N-sulfonyloxazaborolidinone as a catalyst. The polymerization occurred smoothly at low temperature (−78°C to −20°C) to afford optically active polymers having unique main-chain structure of β-hydroxy carbonyl repeating unit. In order to estimate the asymmetric induction during the
双(三乙基甲硅烷基烯醇醚)和二醛的不对称醛醇缩合聚合反应是在手性N-磺酰基氧杂氮杂硼硼烷酮作为催化剂的存在下进行的。聚合在低温(-78℃至-20℃)下平稳地进行,以提供具有独特的β-羟基羰基重复单元的主链结构的光学活性聚合物。为了估计聚合过程中的不对称诱导,以三乙基甲硅烷基烯醇醚和苯甲醛的不对称醛醇缩合反应为模型反应。由(R)-O-乙酰基扁桃酸手性衍生后,通过1 H NMR分析测定由不对称聚合得到的手性聚合物的光学纯度。