A facile route to 1H- and 2H-indazoles from readily accessible acyl hydrazides by exploiting a novel aryne-based molecular rearrangement.

André Shamsabadi,Vijay Chudasama

doi:10.1039/c8cc06556j

Abstract

Herein we report the transformation of readily synthesised acyl hydrazides into 2-hydrazobenzophenones via a novel molecular rearrangement pathway using aryne chemistry. The developed reaction protocol is performed under relatively mild conditions and is tolerant of a wide variety of functional groups, and the 2-hydrazobenzophenone products provide access to both 1H- and 2H-indazoles from a single intermediate.

Highlights

We report the transformation of readily synthesised acyl hydrazides into 2-hydrazobenzophenones via a novel molecular rearrangement pathway using aryne chemistry
The developed reaction protocol is performed under relatively mild conditions and is tolerant of a wide variety of functional groups, and the 2-hydrazobenzophenone products provide access to both 1Hand 2H-indazoles from a single intermediate
Most strategies for the synthesis of indazoles are generally limited by their requirement of using complex multi-step syntheses,[11] and/or using harsh reaction conditions that often promote alternative reaction pathways[12] and/or poor functional group tolerance.[13]

Summary

Introduction

A facile route to 1H- and 2H-indazoles from readily accessible acyl hydrazides by exploiting a novel aryne-based molecular rearrangement† We report the transformation of readily synthesised acyl hydrazides into 2-hydrazobenzophenones via a novel molecular rearrangement pathway using aryne chemistry. The developed reaction protocol is performed under relatively mild conditions and is tolerant of a wide variety of functional groups, and the 2-hydrazobenzophenone products provide access to both 1Hand 2H-indazoles from a single intermediate.

Results

Conclusion