Chiral Ti complexes, which are constituted of 3,3′-modified-biphenolate (BIPOLate) ligands atropisomerically controlled by (R)-TADDOLs, are shown to be novel chiral Lewis acid catalysts for the methylation reaction of aldehydes with an achiral methyl-titanium reagent. Thus, the chiral 3,3′-modified BIPOLate/TADDOLate-Ti complexes give enhanced enantioselectivities up to 100% enantiomeric excess.
3,3′ 改性联
苯酚(BIPOLate)
配体由 (R)-TADDOLs 异构体控制构成的手性 Ti 复合物是新型手性
路易斯酸催化剂,可用于醛与非手性甲基
钛试剂的甲基化反应。因此,手性 3,3′ 改性 BIPOLate/TADDOLate-Ti 复合物的对映体选择性增强,对映体过量率高达 100%。