Cyclic ketones enantioselective fluorinations

Enantioselective a-fluorination of cyclic ketones can be achieved with excellent enantioselectivity by the use of NFSi in the presence of a primary amine functionalized cinchona alkaloid catalyst (eq 29). ... 

Kwiatkowski P, Beeson TD, Conrad JC, MacMillan DWG. Enantioselective organocatalytic a-fluorination of cyclic ketones. J. Am. Chem. Soc. 2011 133 1738-1741. 

The organocatalysed asymmetric cycloaddition reaction of a,p-unsaturated ketones and aldehydes is scarcely studied, especially for fluorine-containing substrates. In this area, Liu et al. have reported unusual inverse-electron-demand oxa-Diels-Alder reactions of a,p-unsaturated trifluoromethyl ketones with aldehydes catalysed by chiral a,a-diphenylprolinol trimethylsilyl ether. It was shown that the addition of pura-fluorophenol and silica gel along with this catalyst was necessary, otherwise the reaction was very slow and a poor yield was obtained. Under these optimal conditions, the expected cyclic adducts were obtained in good yields and high fl n-diastereo- and enantioselectivities, as shown in Scheme 6.11. 

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