Stereoselective synthesis of octahydro-3bH-[1,3]dioxolo[4″,5″:4′,5′]furo[2′,3′:5,6]pyrano[4,3-b]quinolines via intramolecular hetero-Diels–Alder reactions catalyzed by bismuth(III) chloride

A new, efficient and stereoselective synthesis of furo[2′,3′:5,6]pyrano[4,3-b]quinoline derivatives 3 and 3′ has been achieved by intramolecular hetero–Diels–Alder reactions of aldimines generated in situ from aromatic amines and the O-allyl derivative of the chiral sugar derived aldehyde 2 in acetonitrile in the presence of a catalytic amount of BiCl3. The products are formed with extremely high trans selectivity in good to excellent yields.