Regiodirectivity of ring-opening of 2,3-epoxyperfluoroalkanes by nucleophilic reagents

Abstract

2,3-epoxyperfluoroalkanes ( I–IV) with nucleophilic reagents are shown to yield mixtures of products derived from initial attack of nucleophiles at both of the ring carbon atoms. The ratios of directions of ring opening (A/B) were established using 19F NMR spectroscopy. The data obtained are summarized in the table (mol.%). ▪ No R F Nucleophilic reagents F − CH 3ONa LiAlH 4 NH 3 A B A B A B A B I C 2F 5 55 45 24 76 26 74 20 80 II C 3F 7 74 26 45 55 42 58 37 63 III C 5F 11 77 23 63 37 46 54 50 50 IV CF(CF 3) 2 100 - 92 8 90 10 100 - The effects of the epoxide structure and properties of the reagent on regiodirectivity of ring opening will be discussed. The regiospecific opening of epoxy-ring ( IV) by nucleophiles can be explained by steric factors.