Identification of Ammonium Chloride as an Effective Promoter of the Asymmetric Hydrogenation of a -Enamine Amide

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• 作者：Andrew M. Clausen ; Brianne Dziadul ; Kristine L. Cappuccio ; Mahmoud Kaba ; Cindy Starbuck ; Yi Hsiao ; Thomas M. Dowling
• 刊名：Organic Process Research & Development
• 出版年：2006
• 出版时间：July 2006
• 年：2006
• 卷：10
• 期：4
• 页码：723 - 726
• 全文大小：65K
• 年卷期：v.10,no.4(July 2006)
• ISSN：1520-586X

文摘

An investigation into the cause of substrate specific hydrogenation performance variability was conducted. A significant andunexpected correlation was observed between apparent pH ofa solution of the substrate and rate of conversion and enantioselectivity. This observation led to the examination of low andvariable levels of native ammonium chloride in different lotsof substrate. The presence of ammonium chloride was foundto have a positive effect on reaction rate and enantioselectivitywhen controlled within a relatively narrow range. Optimalperformance was achieved with a mole ratio of 1:1 ammoniumchloride to catalyst.