Regio- and Diastereoselective 1,3-Dipolar Cycloaddition between Perfluoro-2-methyl-2-pentene and Nitrones: A Facile Approach to Partially-Fluorinated Isoxazolidines

Regio- and Diastereoselective 1,3-Dipolar Cycloaddition between Perfluoro-2-methyl-2-pentene and Nitrones: A Facile Approach to Partially-Fluorinated Isoxazolidines

Regio- and diastereoselective 1,3-dipolar cycloaddition reactions of nitrones {(Z)-${\alpha}$-phenyl-N-methylnitrone (1a) and (Z)-${\alpha}$-propyl-N-butylnitrone (1b)} with electron-deficient perfluoro-2-methyl-2-pentene (2) lead to novel isoxazolidines {5-fluoro-5-pentafluoroethyl-4,4-bis-trifluoromethyl-2-methyl-3-phenyl-isoxazolidine (3a) and 2-butyl-5-fluoro-5-pentafluoroethyl-4,4-bis-trifluoromethyl-3-propyl-isoxazolidines (3b) respectively} as major constituents. These derivatives were characterized by IR, $^1H$ and $^{19}F$ NMR, GC-MS and NOE measurements, and the absolute structure of 3a was confirmed by X-ray crystallography.