Dearomative Dichloromethylation of Chromium-Bound Arenes and Formal Arene C–H Dichloromethylation

The dichloromethyl group is a valuable functional motif in bioactive molecules and synthetic chemistry. Despite its utility, the dearomative dichloromethylation of arenes remains a significant challenge and has been largely unexplored. Herein, we develop a chromium η⁶-coordination-enabled strategy for dearomative 1,2-hydrodichloromethylation of arenes using inexpensive CH₂Cl₂ as the dichloromethylating source, providing efficient access to dichloromethylated 1,3-cyclohexadienes. Furthermore, by altering the workup to oxidative quenching with I₂, this system is extended to formal arene C-H dichloromethylation, delivering dichloromethylated arenes directly. The method features a broad substrate scope, excellent functional group compatibility, and successful application in the late-stage modification of complex drug molecules.