Stereoselective Suzuki-Miyaura Cross-Coupling Reactions of Potassium Alkenyltrifluoroborates with Alkenyl Bromides

摘要

The Stereoselective synthesis of conjugated dienes using air-stable potassium alkenyltrifluoroborates as coupling partners is described. The palladium-catalyzed cross-coupling reaction of potassium (E)- and (Z)-alkenyltrifluoroborates with either (E)- or (Z)-alkenyl bromides proceeds readily with moderate to excellent yields to give the corresponding (E,E)-, (E,Z)-, (Z,E)-, or (Z,Z)-conjugated dienes stereospecifically. The cross-coupling can generally be effected using 5 mol % of Pd(OAc)_2, 10 mol % of PPh_3, and 3 equiv of Cs_2CO_3 in THF-H_2O (10:1). A variety of functional groups are tolerated in both coupling partners.