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.