Kinetic Resolution of Unsaturated Amides in a Chlorocyclization Reaction: Concomitant Enantiomer Differentiation and Face Selective Alkene Chlorination by a Single Catalyst

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• 作者：Arvind Jaganathan ; Richard J. Staples ; Babak Borhan
• 刊名：Journal of the American Chemical Society
• 出版年：2013
• 出版时间：October 2, 2013
• 年：2013
• 卷：135
• 期：39
• 页码：14806-14813
• 全文大小：450K
• 年卷期：v.135,no.39(October 2, 2013)
• ISSN：1520-5126

文摘

The first example of a kinetic resolution via chlorofunctionalization of olefins is reported. The enantiomers of racemic unsaturated amides were found to have different hydrogen-bonding affinities for chiral Lewis bases in numerous solvents. This interaction was exploited in developing a kinetic resolution of racemic unsaturated amides via halocyclization. The same catalyst serves to both 鈥渟ense chirality鈥?in the substrate as well as mediate a highly face-selective chlorine delivery onto the olefin functionality, resulting in stereotriad products in up to 99:1 dr and up to 98.5:1.5 er. The selectivity factors were typically greater than 50 to allow for the simultaneous synthesis of both the products and unreacted substrates in highly enantioenriched form at yields approaching 50%. The reaction employs catalytic amounts (鈮?.50 mol %) of a commercially available and recyclable organocatalyst.