# Dimerization of Allylbenzenes into Cyclolignans by a Metathesis-Oxidation Sequence

## TL;DR

A new chemical method combines metathesis and oxidation to efficiently produce cyclolignan compounds, which are important in natural product chemistry.

## Contribution

A scalable one-pot metathesis-oxidation sequence for synthesizing cyclolignans with mechanistic insights.

## Key findings

- A two-step sequence produces cyclolignans via Ru-catalyzed metathesis and oxidation.
- Changing oxidation conditions yields benzyl styryl ketones instead of cyclolignans.
- The oxidation mechanism involves single electron transfer and proton transfer steps.

## Abstract

Allylbenzenes form
dimeric cyclolignans in a two-step, one-pot
sequence involving Ru-catalyzed olefin metathesis followed by iron-
or acid-catalyzed oxidation with DDQ. Alternatively, performing the
oxidation step under wet conditions leads to benzyl styryl ketones
as the major products. The mechanistic investigation suggests that
the oxidation process relies on the combination of single electron
transfer, hydrogen atom transfer, and proton transfer steps. The developed
metathesis-oxidation sequence enables a straightforward and scalable
preparation of arylnaphthalene and aryltetralin types of cyclolignans,
such as oleralignan B and its derivatives.