Highly Enantioselective Mukaiyama Aldol Reaction of α,α-Dichloro Ketene Silyl Acetal: An Efficient Synthesis of a Key Intermediate for Diltiazem
作者:Ritsuo Imashiro、Tooru Kuroda
DOI:10.1021/jo026361+
日期:2003.2.1
and high enantioselectivity (96% ee), together with the chiral ligand 13a in nearly quantitative recovery. The reaction using a substoichiometric amount of 12e (20 mol %) also proceeded to excellent yield (88%), with somewhat lower enantioselectivity (77% ee). The aldol product 3a thus obtained was easily converted to (-)-2 in excellent yield (80%) and high optical purity (>99% ee). The highly enantioselective
在高对映选择性的Mukaiyama aldol反应的基础上,已开发出一种有效的合成(2R,3S)-3-(4-甲氧基苯基)缩水甘油酸甲酯(-)-2(地尔硫卓(1)的关键中间体)的方法。茴香醛(4a)与α,α-二氯乙烯酮甲硅烷基乙缩醛5。因此,使用化学计量的手性草氮杂硼烷酮催化剂12a进行反应,与手性配体一起,可实现出色的收率(83%)和高对映选择性(96%ee) 13a几乎定量回收。使用亚化学计量的12e(20 mol%)进行的反应也以优异的收率(88%)进行,对映选择性略低(ee为77%)。由此获得的醛醇缩合产物3a易于以优异的产率(80%)和高的光学纯度(> 99%ee)转化为(-)-2。12a催化的具有5的高对映选择性Mukaiyama aldol反应被证明适用于各种醛。还描述了由廉价的起始原料有效制备5。