Novel palladium chiral phosphino-oxazoline complexes: Crystal structure studies and application to asymmetric Heck reaction

The novel palladium(II) complexes coordinated with (S,S)- and (S,R)-2-[4-(i sopropyl)oxazol-2-yl]-2'-diphenylphosphino-1,1'-binaphthyls (1a and 1b) wer e prepared and their structures were determined by X-Ray crystallography. T he X-Ray single crystal structure studies reveal that the axially chiral bi naphthyl skeletons are more strongly regulating the chiral environment arou nd the palladium centers than the chiral carbon centers in the oxazoline mo ieties. The results from application of 1a and 1b to the asymmetric Heck re action also supported this conclusion. 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.