Ortho-benzyl alcohol-directed multicomponent cascade reaction: a concise and practical synthesis of pyrroloquinolinediones

Aliphatic alcohol hydroxyl or phenolic hydroxyl as a directing group has proved to be a versatile functional group and widely used in organic synthesis, however, ortho-benzyl alcohol used as a directing group has never been reported. We herein described an unprecedented multicomponent tandem reaction to assemble structurally diverse pyrroloquinolinediones (28 examples, 70-87% yields) starting from readily available raw materials under mild conditions. Significantly, this unique transformation involved an ortho-benzyl alcohol as directing group to promote a cascade reaction to the synthesis of functionalized aminomaleimides (29 examples, 71-91% yields), which then underwent I2-oxidized tandem annulations. This concise, environmentally friendly and practical protocol to the preparation of a series of potentially valuable N-fused heterocycles involved the formation of new multiple chemical bonds (C=N, 2C-N, C-C) in a one-pot fashion.