A microwave-assisted tandem [3+2] cycloaddition/retro-Diels–Alder reaction of azomethine ylides derived from imines of α-aminoesters to dimethyl 7-oxabicyclo[2.2.1]hepta-2,5-diene-2,3-dicarboxylate derivatives is described. The procedure delivers, in a short reaction time, pyrrolines in high yields. In a such sequence, the oxanorbornadiene derivatives behave as masked forms of dimethyl acetylenedicarboxylate