Simple and efficient access to tetrahydrofurans, tetrahydropyrans, and pyrrolidines through a tandem cross-metathesis/1,4-addition process from (E)-dimethyl2-oxopent-3-enylphosphonate and N-protected ω-unsaturated amines or alcohols under microwave irradiation is described. As the Grubbs–Hoveyda catalyst is highly chemoselective, a diversity of functionalizedheterocycles were synthesized. Furthermore