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 gamma-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 degrees C in the presence of K2CO3 (3 equiv.) in H2O-MeOH (9/1).