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Letters in Organic Chemistry

Author(s): Ya-Xi Yang, Zheng Li, Guo-Rong Chen and Yuan-Chao Li

DOI: 10.2174/157017810790796237

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Phase-Transfer Catalysed Enantioselective Epoxidation of Estra-Δ5(10),9(11)-diene Using Chiral Ammonium Salts Derived from Cinchona Alkaloids

Page: [163 - 167] Pages: 5

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Abstract

A modified phase-transfer catalysed enantioselective epoxidation of estra-Δ5(10),9(11)-diene, an important intermediate of anti-early pregnancy drug mifepristone 1, have been determined and investigated. Eight chiral ammonium salts (PTC A-H), used as phase-transfer catalysts, have been synthesized from cinchona alkaloids. Among them, PTC G and PTC H have exhibited satisfying catalytic activity to improve the ratio of α/β epoxide up to 7:1.

Keywords: Mifepristone, estra-Δ5(10),9(11)-diene, cinchona alkaloids, chiral ammonium salts