# Hydrazine Derivatives as C-Centered Radical Precursors for C-C Bond Formation Reactions

## TL;DR

This paper reviews how hydrazine derivatives can generate carbon-centered radicals for forming carbon-carbon bonds in organic synthesis.

## Contribution

The novelty lies in summarizing the use of monosubstituted hydrazine derivatives as efficient radical precursors for C-C bond formation.

## Key findings

- Monosubstituted hydrazine derivatives are stable and atom-efficient sources of C-centered radicals.
- They are used in alkene difunctionalization and cascade cyclization reactions.
- They enable CH-functionalization of arenes via radical addition and re-aromatization.

## Abstract

Organic monosubstituted hydrazine derivatives (Ar-NHNH2, RC(O)-NHNH2, Alkyl-NHNH2) are synthetically available, atom-efficient and stable sources of C-centered radicals upon oxidation with extrusion of the energetically favorable N2 molecule. This review summarizes the synthetic application of monosubstituted hydrazine derivatives (arylhydrazines, carbazates, acylhydrazides, hydrazine carboxamides and alkylhydrazines) in free-radical C-C bond-forming reactions. The main application directions in this field are (a) alkene difunctionalization, (b) cascade cyclization initiated by the addition of hydrazine-derived C-centered radicals to acrylamides and isonitriles, and (c) CH-functionalization of (hetero)arenes via C-centered radical addition followed by oxidative dehydrogenation (re-aromatization).