The palladium-catalyzed cross-coupling reaction of 9-organothio-9-borabicyclo[3.3.1]nonanes with organic electrophiles: Synthesis of unsymmetrical sulfides

The synthesis of unsymmetrical sulfides was carried out in high yields by the palladium-catalyzed cross-coupling reaction of 9-organothio-9-borabicyclo[3.3.1]nonane (9-RS-9-BBN) with organic electrophiles, such as iodoarenes, 1-iodo-1-alkenes, allyl carbonate and propargyl carbonate, Iodoarenes and 1-iodo-1-alkenes were smoothly converted into the corresponding sulfides at 50 degrees C in the presence of PdCl2(dppf) (3 mol%) and K3PO4 (3 equiv.) in DMF. In contrast, the cross-coupling reaction of 9-RS-9-BBN with allyl or propargyl carbonates occurred in DMF without the assistance of a base. Both reactions catalyzed by Pd(dba)(2)-dppf regioselectively produced allyl and allenyl sulfides in excellent yields. The scope and limitations of the reactions, as well as the effects of varying the reaction conditions, are discussed.