Pd-Catalyzed Selective Bifunctionalization of 3-Iodo-o-Carborane by Pd Migration

A palladium-catalyzed highly selective 3,4-bifunctionalization of 3-I-o-carborane has been developed, leading to the preparation of 3-alkenyl-4-R-o-carboranes (R=alkyl, alkynyl, aryl, allyl, CN, and amido) in high to excellent yields. This protocol combines the sequential activation of cage B(3)-I and B(4)-H bonds by Pd migration from exo-alkenyl sp(2) C to cage B(4), which is driven by thermodynamic force. This represents a brand-new strategy for selective bifunctionalization of carboranes with two different substituents.