Palladium-Catalyzed Selective Mono-Chlorination of o-Carboranes: Changing the Concept of FeCl3 from Lewis Acid to Chlorine Source in Carboranes

A palladium catalyzed selective mono-chlorination of o -carboranes has been developed by utilization the oxidizability of FeCl 3 , and a series of mono-chlorinated o -carboranes with active groups have been synthesized with moderate to good yields as well as good selectivity. A plausible mechanism involving the electrophilic palladation of B-H bond and the Pd(II)/Pd(IV) catalytic cycle was proposed. Graphical One stone two birds: By utilization the dual role of FeCl 3 with oxidizability and chlorine source, the selective mono-chlorination of o -carboranes on B(9) and B(8) have been developed. The concept that FeCl 3 only as a Lewis acid in promoting the electrophilic halogenation of carboranes has been changed.