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Chiral Fluoro Ketones for Catalytic Asymmetric Epoxidation of Alkenes with Oxone

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journal contribution
posted on 17.04.2002, 00:00 by Scott E. Denmark, Hayao Matsuhashi
Two structurally dissimilar, chiral fluoro ketones have been prepared and their potential as enantioselective catalysts for asymmetric epoxidation with Oxone has been evaluated. The tropinone-based ketone (−)-5 was easily prepared and showed excellent reactivity but only modest enantioselectivity. The biphenyl-based ketone (−)-6 was prepared in a somewhat lengthy synthesis (along with its monofluoro and geminal fluoro analogues). This ketone exhibited only modest reactivity; 30 mol % of (−)-6 was needed to bring about complete conversion in a reasonable time. The enantioselectivity of this catalyst was generally much higher, but again very substrate dependent.