# Synthesis of Sterically Congested Carbonyl Compounds via an ipso-Selective Sulfonium Rearrangement

## TL;DR

A new method is introduced for making crowded carbonyl compounds using a sulfonium rearrangement, which works well where traditional methods fail.

## Contribution

The ipso-selective sulfonium rearrangement provides a novel, metal-free route for synthesizing sterically congested α-arylated carbonyl compounds.

## Key findings

- The method enables synthesis of α-arylated carbonyl compounds that are difficult to make via traditional cross-coupling.
- The sulfonium-based rearrangement is robust against steric hindrance.
- This approach is orthogonal to metal-catalyzed strategies.

## Abstract

Despite the success
of metal-catalyzed
cross-coupling strategies
to assemble a variety of C–C bonds, the synthesis of sterically
congested α-arylated carbonyl compounds remains a difficult
task. Herein, we present an ipso-rearrangement approach
relying on electron redistribution in sulfonium intermediates. This
modular method enables the synthesis of a variety of α-arylated
carbonyl compounds and is orthogonal to traditional metal-catalyzed
cross-coupling strategies. More importantly, it demonstrated remarkable
robustness toward steric hindrance and allowed us to efficiently forge
congested C–C bonds.