Quasiracemic Synthesis: Concepts and Implementation with a Fluorous Tagging Strategy to Make Both Enantiomers of Pyridovericin and Mappicine

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• 作者：Qisheng Zhang ; Alexey Rivkin ; and Dennis P. Curran
• 刊名：Journal of the American Chemical Society
• 出版年：2002
• 出版时间：May 22, 2002
• 年：2002
• 卷：124
• 期：20
• 页码：5774 - 5781
• 全文大小：165K
• 年卷期：v.124,no.20(May 22, 2002)
• ISSN：1520-5126

文摘

The concept of quasiracemic synthesis is introduced and illustrated with syntheses of bothenantiomers of pyridovericin (whose absolute configuration is assigned as R) and mappicine. Like racemicsynthesis, quasiracemic synthesis provides both enantiomers in a single synthetic sequence; however,separation tagging is used to ensure that quasiracemic mixtures can be analyzed, separated, and identifiedon demand. Fluorous tags of differing chain lengths are used to tag two enantiomeric starting materials.The resulting quasienantiomers are mixed to make a quasiracemate, which is then treated like a trueracemate in successive steps of the synthesis. Fluorous chromatography is used to separate, or demix,the final quasiracemate into its two components, which are then detagged to provide (true) enantiomericproducts. Quasiracemic synthesis is portrayed as the first and simplest of a series of mixture synthesistechniques based on separation tagging, and the prospects for using other types of separation tags arebriefly evaluated.