A New Optically Active Monodentate Phosphine Ligand, (<i>R</i>)-(+)-3-Diphenylphosphino-3′-methoxy-4,4′-biphenanthryl (MOP-phen): Preparation and Use for Palladium-Catalyzed Asymmetric Reduction of Allylic Esters with Formic Acid
作者:Tamio Hayashi、Hiroshi Iwamura、Yasuhiro Uozumi、Yonetatsu Matsumoto、Fumiyuki Ozawa
DOI:10.1055/s-1994-25517
日期:——
(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 Ï-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.
(R)-(+)-3-二苯基膦-3′-甲氧基-4,4′-双菲基(MOP-phen,8)的制备始于(-)-3,3′-二羟基-4,4′-双菲基。通过其π-烯丙基钯络合物的X射线晶体结构分析,确定了(+)-8的绝对构型为R。单齿光学活性膦配体8被发现比(R)-(+)-2-二苯基膦-2′-甲氧基-1,1′-联萘基(MOP,1a)在钯催化的烯丙基酯不对称还原反应中具有更高的对映选择性,使用甲酸作为还原剂可得到高达85% ee的光学活性烯烃。