Highly para-Selective C-H Alkylation of Benzene Derivatives with 2,2,2-Trifluoroethyl α-Aryl-α-Diazoesters

Compared to the most popular directing-group-assisted strategy, the undirected strategy for C-H bond functionalization represents a more flexible but more challenging approach. Reported herein is a gold-catalyzed highly site-selective C(sp(2))-H alkylation of unactivated arenes with 2,2,2-trifluoroethyl alpha-aryl-alpha-diazoesters. This protocol demonstrates that high site-selective C-H bond functionalization can be achieved without the assistance of a directing group. In this transformation, both the gold catalyst and trifluoroethyl group on the ester of the diazo compound play vital roles for achieving the chemo-and regioselectivity.