# Ketone Oximes as NO2 Radical Precursors for Regioselective Iodo–Nitrosylative Cyclization of Unactivated 1,6-Enynes

## TL;DR

A new chemical method uses ketone oximes to create complex molecules from simple starting materials without metals or catalysts.

## Contribution

Introduces oximes as a new, stable source of NO2 radicals for selective chemical reactions.

## Key findings

- The method enables a metal-free cascade reaction of unactivated 1,6-enynes.
- It produces 4-(iodo(phenyl)methylene)-3-(nitromethyl)-1-tosylpyrrolidines through a selective sequence.
- Oximes are shown to be effective and stable NO2-radical donors for such transformations.

## Abstract

A metal-free three-component
radical cascade cyclization of unactivated
1,6-enynes has been developed using 1-phenylethan-1-one oxime as a
novel in situ nitrogen dioxide (NO2) radical source under
I2/aqueous TBHP conditions. This transformation proceeds
through a chemo- and regioselective sequence involving NO2· addition to the terminal alkene, 5-exo-dig cyclization onto
the alkyne, and iodine trapping of the resulting carbon-centered radical,
yielding 4-(iodo­(phenyl)­methylene)-3-(nitromethyl)-1-tosylpyrrolidines.
This strategy avoids transition metals, photocatalysts, or prefunctionalized
nitrogen reagents and highlights the previously unexplored potential
of oximes as bench-stable NO2-radical donors for cascade
transformations.