Syntheses of optically active trifluoronorcoronamic acids

[GRAPHICS] Syntheses of optically active trifluoronorcoronamic acid 6 and its diastere omer 9 are described. Highly stereospecific and diastereoselective S(N)2 cy clization of gamma-cyanohydrins 3a and 3b gave cydopropyl nitriles 4a and 4 b. Hydrolysis of the cyano group and deprotection of the amino group of 4a provide trifluoronorcoronamic acid 6, Hofmann rearrangement of the amide wh ich was generated by hydrolysis of the cyano group and oxidative cleavage o f the aryl ring of 4b to provide trifluoro-allo-norcoronamic acid 9.