Luxury of N‐Tosylhydrazones in Transition‐Metal‐Free Transformations

Abstract

AbstractThis review is focused on the recent developments in transition‐metal‐free transformations using N‐tosylhydrazones, emerging building blocks in contemporary organic chemistry. Emphasis is given to their synthetic potential, scope, mechanism and limitations. N‐Tosylhydrazones, derivatives of carbonyl compounds, can undergo a wide range of reactions under transition‐metal‐free reaction conditions. The chemical behaviour of tosylhydrazones is unique under different reaction conditions as they can act as diazo precursors, carbene sources, 1,3‐dipoles, ambiphilic reagents, one‐carbon synthons, and an alternative to the parent carbonyl compounds. These diverse reactivities have resulted in the development of novel C−C and C−heteroatom bond‐forming reactions. The potential of N‐tosylhydrazones in transition‐metal‐free reactions is evident from the synthesis of a handful of molecules such as cyclopropanes, di‐ and triarylmethanes, pyrazoles, triazoles, pyridazines, ethers, carbamates, thioacetals, thiadiazoles and many others.magnified image