Palladium-Catalyzed Selective Mono-/Tetraacetoxylation of o-Carboranes with Acetic Acid via Cross Dehydrogenative Coupling of Cage B-H/O-H Bonds.

A selective mono-/tetraacetoxylation of o-carboranes with acetic acid via cross dehydrogenative coupling of cage B-H/O-H bonds has been developed, and a series of mono- and tetraacetoxylated o-carboranes have been synthesized with moderate to good yields as well as good selectivity. Mechanistic studies indicate that the acetoxyl originates from acetic acid directly, and a nucleophilic addition of PdIV-oxo species and dehydration process is proposed.