# A Comprehensive Review of Radical-Mediated Intramolecular Cyano-Group Migration

## TL;DR

This paper reviews the development and mechanisms of a chemical process that moves cyano groups within molecules using radical reactions.

## Contribution

The paper provides a comprehensive and organized review of radical-mediated cyano-group migration strategies from 1961 to 2025.

## Key findings

- Four main strategies for generating initial carbon radicals are identified and analyzed.
- The review highlights reaction conditions, substrate scope, and mechanistic insights for each strategy.
- The field has seen significant growth in the past two decades due to advances in radical chemistry and photocatalysis.

## Abstract

The radical-mediated intramolecular translocation of cyano groups has been recognized as a useful tool for the site-selective functionalization of organic molecules. The process is believed to proceed through the addition of an in situ-generated carbon-centered radical to the nitrile triple bond, followed by the β-scission of the resulting cyclic iminyl radical intermediate to relocate the cyano group and produce a more stable carbon radical for further elaboration. Beginning in the early 1960s and continuing for the next forty years, the research in this particular area has seen a surge of growth during the past two decades with advancements in radical chemistry and photocatalysis. The present article attempts to conduct a comprehensive review of existing studies on this topic by covering the literature from 1961 to 2025. The procedures developed for the purpose are grouped and discussed in four sections according to the strategies used to generate the initial carbon radicals, which include (i) hydrogen-atom transfer (HAT), (ii) radical addition to the π system, (iii) halogen-atom transfer (XAT), and (iv) the homolytic fission of a C-C single bond. In each section, a specific emphasis will be placed on reaction conditions, substrate scopes, and mechanisms.