First example of a third generation nitrone cycloaddition

Compounds 5 and 6, derived from the cycloadditions of a nitrone to α,β-unsaturated lactones, were oxidized with m-chloroperbenzoic acid affording regiospecifically aldonitrones, 8 and 14, respectively. These second generation nitrones were reacted with several dipolarophiles yielding cycloadducts 9-13, 15, and 16. A repeated sequence of oxidation-cycloaddition applied to compound 12 allowed the isolation of die first example of a third generation cycloadduct, 17. During this work a series of new highly functionalized pyrrolidines have been prepared.