# Visible light-induced 1,2-alkoxy shift of α-diazoacetates for Wolff rearrangements – access to oxyketenes

## TL;DR

A new method using visible light to rearrange α-diazoacetates into oxyketenes is developed, enabling new chemical reactions.

## Contribution

A visible-light-induced alkoxy shift in α-diazoacetates is introduced, expanding the Wolff rearrangement to generate oxyketenes.

## Key findings

- Visible light induces a 1,2-alkoxy shift in α-diazoacetates to form oxy-substituted ketenes.
- The generated oxyketenes efficiently undergo [2 + 2] cycloadditions with imines and nucleophilic additions with amines.
- The method is scalable and supported by mechanistic and computational studies.

## Abstract

The Wolff rearrangement is an important transformation to access ketenes via 1,2-alkyl or aryl migrations of α-diazoketones. In contrast, alkoxy group migration from free singlet carbenes has remained elusive owing to the intrinsically low migratory aptitude of alkoxy groups. Here we report a visible-light-induced 1,2-alkoxy/aryloxy shift of α-diazoacetates that generates oxy-substituted ketenes. These intermediates undergo efficient [2 + 2] cycloadditions with imines and nucleophilic addition reactions with amines. The method tolerates a wide substrate range, operates on gram scale, and is supported by mechanistic and computational studies. This work expands the scope of Wolff rearrangements and opens new chemical space for oxyketene reactivity.

A visible-light-induced 1,2-alkoxy shift to generate oxy-substituted ketenes via Wolff rearrangement from α-diazoacetates is developed. This approach enables efficient [2 + 2] cycloadditions with imines and nucleophilic additions with amines.