# Benzophenone Oxime Tosylate as the Photoacid Generator for the Friedel–Crafts Arylation of Aldehydes With Indoles

## TL;DR

A new photoacid generator enables efficient Friedel–Crafts arylation of aldehydes with indoles under inert conditions.

## Contribution

A sustainable and efficient Friedel–Crafts arylation method using benzophenone oxime tosylate as a photoacid generator.

## Key findings

- The method achieves good to excellent yields of diarylmethane derivatives.
- Mechanistic studies reveal key intermediates involved in the transformation.
- The reaction works under inert conditions with low catalyst loading.

## Abstract

Photochemistry enables transformations inaccessible through ground‐state pathways. We report a sustainable and operationally simple Friedel–Crafts arylation using benzophenone oxime tosylate, in low catalyst loading, as the photoacid generator under inert conditions. The method accommodates a broad substrate scope, affording diarylmethane derivatives in good to excellent yields. Mechanistic studies elucidate key intermediates driving the transformation.

Friedel–Crafts Arylation of Indoles: Use of an iminosulfonate derivative as the photoacid generator for the Friedel–Crafts arylation reaction between aldehydes and indoles under inert atmosphere.