Three-Component Cycloadditions to Prepare Isooxazoline-Fused Furo[3,2-b]quinolines

A variety of isooxazoline-fused furo[3,2-b]quinolines containing four stereocenters were prepared in 40 %-87 % yields with high regioselectivity and diastereoselectivity. The control experimental results revealed that the reaction underwent in the order of [4+2] cycloaddition and sequential [3+2] cycloaddition between aza-ortho-quinone methides (ao-QM) generated from 2-chloromethyl anilines, furans, and nitrile N-oxides generated from hydroxamoyl chlorides. The present method features mild reaction conditions, broad substrate scope, high diastereoselectivity of four stereocenters, and novel scaffolds of isooxazoline-fused furo[3,2-b]quinolines.