Tandem SNAr/Aldol Condensation of Oxindoles with o-Haloacetophenones Enables Modular Assembly of 2,3-Fused Indolines Bearing a Quaternary Carbon

Described herein is a novel base-promoted [4 + 2] annulation reaction of 3-methyl-indolin-2-ones with ortho-haloacetophenones, which enables the modular and reliable synthesis of 2,3-fused indolines bearing a quaternary carbon. Two C-C bonds can be successively constructed through a tandem sequence involving base-promoted S_NAr and aldol condensation. This protocol is highlighted by transition metal-free conditions, high efficiency, and simple operation.