J. Chem. Soc. Perkin Trans. 1 1997 3043 Influence of a 2-fluoro substituent on diastereoselectivity in the 1, 3-dipolar cycloadditions of nitrones Masataka Ihara,* Yuko Tanaka Nobuyuki Takahashi Yuji Tokunaga and Keiichiro Fukumoto Pharmaceutical Institute Tohoku University Aobayama Sendai 980-77 Japan It is clear