Asymmetric Reactions of Enamines with Methyl (<i>E</i>)-4-Oxo-4-(2-oxo-1,3-oxazolidin-3-yl)-2-butenoate by the Use of a Chiral Titanium Reagent
作者:Yujiro Hayashi、Ken Otaka、Nobuo Saito、Koichi Narasaka
DOI:10.1246/bcsj.64.2122
日期:1991.7
Asymmetric Michael and [2+2] cycloaddition reactions between enamines and methyl (E)-4-oxo-4-(2-oxo-1,3-oxazolidin-3-yl)-2-butenoate proceed with a chiral titanium reagent generated in situ from dichlorodiisopropoxytitanium and a tartrate-derived chiral 1,4-diol. In the presence of excess amounts of the chiral titanium reagent, good to moderate enantioselectivity is attained. The reactions are also well catalyzed even with a catalytic amount of the titanium reagent.
不对称的迈克尔反应和酮的[2+2]环加成反应结合了烯胺与甲基(E)-4-氧代-4-(2-氧代-1,3-噁唑烷-3-基)-2-丁烯酸酯,在反应中使用了现场生成的手性钛试剂,该试剂来自二氯二异丙氧基钛和由酒石酸衍生的手性1,4-二醇。在过量的手性钛试剂存在下,能够获得良好至适中的对映选择性。即使在催化剂量的钛试剂下,反应也能得到很好的催化。