Cycloaddition Reactions of C,N-Diphenylnitrone to Methylene-γ-butyrolactones

[摘要] Cycloaddition of C,N-diphenylnitrone to α-methylene-γ-butyrolactone afforded two diastereomeric 5-spirosubstituted isoxazolidines with high selectivity. Structural assignment was ascertained by NMR studies and an X-ray diffraction experiment on a single crystal of the major isomer and the diastereoselectivity was rationalized on examination of the alternative transition states leading to the two diastereoisomers.

[关键词] Nitrones;lactones;1;3-dipolar cycloaddition;stereoselectivity;regioselectivity