# Eco-Friendly and Efficient Synthesis of 2-Hydroxy-3-Hydrazono-Chromones Through α,β-C(sp2)–H Bond Difunctionalization/Chromone Annulation Reaction of o-Hydroxyaryl Enaminones, Water, and Aryldiazonium Salts

## TL;DR

This paper presents a green and efficient method to synthesize 2-hydroxy-3-hydrazono-chromones using water and common reagents under mild conditions.

## Contribution

The study introduces a novel difunctionalization/annulation strategy for chromone synthesis with broad substrate scope and functional group tolerance.

## Key findings

- The method constructs 2,3-disubstituted chromones with moderate to excellent yields.
- It enables gram-scale synthesis and is applicable to a wide range of substrates.
- The approach is eco-friendly and uses readily available starting materials.

## Abstract

A novel, eco-friendly, and efficient method for constructing 2,3-disubstituted chromone skeletons from readily available water, o-hydroxyaryl enaminones (o-HPEs), and aryldiazonium salts has been developed under mild reaction conditions. This α,β-C(sp2)–H bond difunctionalization/chromone annulation reaction strategy is achieved by building two C(sp3)–O bonds and a C(sp2)-N bond, which provides a practical pathway for the preparation of 2-hydroxy-3-hydrazono-chromones in moderate to excellent yields, enabling broad substrate scope and good functional group tolerance, as well as gram-scale synthesis. This protocol offers a valuable tool for synthesizing diverse functionalized chromones with potential applications in drug discovery and industrial synthesis.