NOVEL PALLADIUM CHIRAL PHOSPHINO-OXAZOLINE COMPLEXES:CRYSTAL STRUCTURE OSTUDIES AND APPLICATION TO ASYMMETRIC HECK REACTION

摘要

The novel palladium(II) complexes coordinated with (S,S)-and (S,R)-2-[4-(isopropyl)oxazol-2-yl]-2'-diphenylphosphino-1,1'-binaphthls (1a and 1b) were prepared and their structures were determined by X-Ray crystallography.The X-Ray single crystal structure studies reveal that the axially chiral binaphthyl skeletons are more strongly regulating the chiral environment around the palladium centers athe the chiral carbon centers in the oxazoline moieties.The results from applkication of 1a and 1b to the asymmetric Heck reaction also supported this conclsion.The highest enantioselectivity (88%ee) was observed in (R)-2-phenyl-2,5-dihydrofuran which was obtained from 2,3-dihydrofuran and phenyl triflate catalyzed by Pd/1a.