Transient Directing Group Strategy as a Unified Method for Site Selective Direct C4-H Halogenation of Indoles.

A unified method for direct C4-H halogenation of indoles has been accomplished with the assistance of anthranilic acids as suitable transient directing groups. Exclusive site selectivity (one out of five potential reactive sites) as well as good functional group tolerance was obtained to install three kinds of halogen atoms (Cl, Br and I, respectively) by using inexpensive -halosuccinimides (NXS) as halogen sources under mild conditions. Taking advantage of the rich functional groups in the product, a diversity of nitrogen-containing heterocycles were facily constructed via one-step late-stage derivations.

Phosphine-Free Ru-Catalyzed Regio- and Stereoselective Addition of Benzoic Acids to Trifluoromethylated Alkynes toward Facile Access to Trifluoromethyl Group-Substituted ()-Enol Esters.

A combination of ruthenium catalyst with silver salt and copper salt was proved to be a highly efficient protocol for the direct addition reaction of benzoic acids with unsymmetrical trifluoromethylated internal alkynes. Diverse trifluoromethyl group-substituted ()-enol esters were readily obtained for a broad substrate scope in moderate to good yields with excellent regio- and stereoselectivities under mild reaction conditions.

Iridium-Catalyzed Regioselective Synthesis of Trifluoromethylated Isocoumarins through Annulation of Benzoic Acids with Trifluoromethylated Alkynes.

An unprecedented Ir-catalyzed oxidative coupling of benzoic acids with trifluoromethylated alkynes was successfully developed to provide diverse trifluoromethylated isocoumarins in moderate to good yields. This new practical procedure was highlighted by mild reaction conditions, broad substrate scope, good regioselectivity, high efficiency, and easy operation.