A Chiral Bimetallic Lewis Acid as a Reaction Template. Asymmetric Reduction of Unsymmetric Ketones with LiBH<sub>4</sub>
作者:Kyoko Nozaki、Kayo Kobori、Toshitsugi Uemura、Takaharu Tsutsumi、Hidemasa Takaya、Tamejiro Hiyama
DOI:10.1246/bcsj.72.1109
日期:1999.5
A new series of chiral bimetallic Lewis acids, 5,5′-bis[(R)-2-aryl-1,3,2-dioxaborolan-4-one], have been prepared from L-(+)-tartaric acid and arylboronic acids. In the presence of these Lewis acids, unsymmetric ketones were reduced quantitatively by LiBH4, in moderate to good ee’s (up to 99% ee). The counter cation of BH4− significantly affects the ee’s of the products. The reaction is applicable to
一系列新的手性双金属路易斯酸,5,5'-bis[(R)-2-aryl-1,3,2-dioxaborolan-4-one],已从 L-(+)-酒石酸和芳基硼酸。在这些路易斯酸的存在下,不对称酮被 LiBH4 以中等至良好的 ee(高达 99% ee)定量还原。BH4- 的抗衡阳离子显着影响产品的ee。该反应适用于芳基烷基酮、二烷基酮和二芳基酮。