Bromination of Ketones by Palladium(II). An Asymmetric α-Bromoketones Catalytically Synthesized by a Mono Palladium(II) Catalyst

The oxidation of ketones by monometallic [pd(ch3cn)2(s)-tol-binap](bf4)2 a or [pd(ch3cn)2(s)-metbox](bf4)2 b in aqueous thf containing copper(ii) bromide produced chiral α-bromoketones. the α-bromoketone products were obtained with moderate to high enantiomeric excess (68-89% ee) and good isolated yields (70-90%). the highest optical purities were 89% ee for cycloheptanone. catalyst b gave slightly higher enantioselectivities than catalyst a. all symmetric ketones gives only one product whereas, oxidation of 2-butanone gives the 3-bromo-2-butanone and 1-bromo-2-butanone. the α-bromoketone products were characterized by ftir, 1h, 13c-nmr and gc/ms.