A new optically active monodentate phosphine ligand, (R)-(+)-3-diphenylphosphino-3'-methoxy-4,4'-biphenanthryl (MOP-phen): Preparation and use for palladium-catalyzed asymmetric reduction of allylic esters with formic acid

Article abstract of DOI:10.1055/s-1994-25517

(R)-(+)-3-Diphenylphosphino-3'-methoxy-4,4'-biphenanthryl (MOP-phen, 8) was prepared starting with (-)-3,3'-dihydroxy-4,4'-biphenanthryl. The absolute configuration of (+)-8 was determined to be R by X-ray crystal structure analysis of its π-allylpalladium complex. The monodentate optically active phosphine 8 was found to be a more enantioselective ligand than (R)-(+)-2-diphenylphosphino-2'-methoxy- 1,1'-binaphthyl (MOP, 1a) for palladium-catalyzed asymmetric reduction of allylic esters with formic acid giving optically active olefins of up to 85% ee.