DMAP-promoted [4 + 2]/[3 + 3] Annulation Cascade Reaction of Morita–Baylis–Hillman Carbonates with Conjugated Imines to Access Functionalized Benzo[c][2,7]naphthyridine Skeletons

Abstract

A novel, synthetically straightforward, selective DMAP-promoted [4 + 2]/[3 + 3] annulation domino reaction of o-acylamino-aryl Morita−Baylis−Hillman (MBH) carbonates with α,β-unsaturated imines to construct complex fused [2,7]naphthyridine frameworks has been developed. The reaction provides a step-economic strategy for the direct synthesis of functionalized benzo[c][2,7]naphthyridines containing three stereogenic centers in high yields with excellent chemo-, regio-, and diastereoselectivity under mild reaction conditions. More importantly, this transformation enables the simultaneous formation of four new bonds and two new six-membered N-heterocycles in only one step. Additionally, the synthetic utility of this method has been demonstrated through its application in the late-stage modification of pharmaceutically active molecules.