Visible-light-induced direct 3-ethoxycarbonylmethylation of 2-aryl-2H-indazoles in water

Abstract

A visible-light-driven rhodamine B-catalyzed transition-metal-free 3-ethoxycarbonylmethylation of 2-aryl-2H-indazoles and imidazo[1,2-a]pyridines (40 examples) using commercially available α-bromoesters was realized in water. This protocol features sustainability, operational simplicity, mild reaction conditions, and remarkable substrate scope. Importantly, α-bromoamides are also appropriate substrates for affording 3-carbamylmethylation products. It could be used for the synthesis of the drug zolpidem and the late-stage modification of natural products.