Palladium-Catalyzed Cascade Deboronation/Regioselective B-P Coupling of closo-Carboranes

A cascade deboronation/regioselective B-P coupling of closo-carboranes is disclosed using a combination of palladium catalysts and nitrogen or phosphine-containing directing groups. Unsymmetric C-substituted closo-carboranes, including C-monosubstituted and unsymmetric 1,2-disubstituted closo-carboranes, are tolerated. Select closo-carboranes bearing other directing groups, such as benzoxazole, and diphenylphosphine, are compatible substrates for this reaction. Phosphine and arsenic can be utilized as effective coupling partners. Furthermore, a catalytic amount of palladium salt mediates the regioselective B-H activation process. Readily available closo-carboranes as the starting materials for direct one-pot synthesis of functionalized nido-carboranes and the in-situ formation of nido-carborane intermediates without purification are important features in terms of practical applications.