Asymmetric Cross-coupling of Potassium 2-Butenyltrifluoroborates with Aryl and 1-Alkenyl Bromides Catalyzed by a Pd(OAc)2/Josiphos Complex

The asymmetric cross-coupling reaction of [CH3CH=CHCH2BF3]K with aryl or 1-alkenyl bromides selectively occurred at the γ-carbon of 2-butenylborane moiety with regioselectivities in a range of 84–99%. The enantioselectivities were in a range of 77–90%ee when a palladium/CyPF-t-Bu complex was used at 80 °C in the presence of K2CO3 (3 equiv.) in H2O–MeOH (9/1).