Imino Diels–Alder reactions: an efficient one-pot synthesis of pyrano and furanoquinoline derivatives catalyzed by SbCl3

Antimony trichloride (SbCl3) was found to be an efficient catalyst for the inverse electron demand imino Diels–Alder reactions of in situ generated N-benzylidenes with 3,4-dihydro-2H-pyran and 2,3-dihydrofuran to afford pyrano and furano[3,2-c]quinolines in excellent yields.