# Controlled formation of versatile methylated compounds based on ring opening of 4-methyl-1-siloxy-1,4-epoxy-1,4-dihydrobenzene

## TL;DR

A new method is developed to form methylated compounds through controlled chemical transformations.

## Contribution

A novel FeCl3-catalyzed ring-opening reaction with regioselective methyl shift is introduced.

## Key findings

- Desilylative ring opening produces 4-hydroxy-4-methyl-2,5-cyclohexadienone.
- CO2Me induces a regioselective C4 to C3 methyl shift to form 6-methyl-2,4-cyclohexadienone.
- The product contains a methyl-substituted quaternary carbon center useful for further synthesis.

## Abstract

We report an FeCl3-catalyzed transformation of 4-methyl-1-siloxy-1,4-epoxy-1,4-dihydrobenzene. Reaction in toluene gave the phenol product, whereas the addition of i-PrOH in 1,2-dichloroethane induced desilylative ring opening to produce 4-hydroxy-4-methyl-2,5-cyclohexadienone, which subsequently underwent a CO2Me-induced regioselective 1,2-methyl shift (C4 to C3) to afford 6-methyl-2,4-cyclohexadienone. This product bears a methyl-substituted quaternary carbon center that is difficult to access by existing methods and serves as a versatile intermediate for further structural elaboration. These results highlight a new mode of skeletal rearrangement and demonstrate regioselective control over competing reaction pathways.

We report an FeCl3-catalyzed transformation of 4-methyl-1-siloxy-1,4-epoxy-1,4-dihydrobenzene.