TiCl4 has given access to the corresponding 2,4-anti-4,5-syn aldol adducts with the highest diastereomeric ratios. The excellent stereocontrol exerted by the aforementioned ketone has been demonstrated in double asymmetric reactions involving chiral α-methyl-β-OTBDPS aldehydes.
路易斯酸的存在极大地改变了基于(S)-2-苄氧基-
3-戊酮1的
钛介导的羟醛工艺的立体选择性。在所调查的
路易斯酸中,TiCl 4获得了具有最高非对映异构体比例的相应2,4-抗-4,5-顺式羟醛加成物。在涉及手性α-甲基-β-OT
BDPS醛的双不对称反应中,已经证明了上述酮发挥的优异的立体控制作用。