An Allyltitanium Derived from Acrolein 1,2-Dicyclohexylethylene Acetal and (η<sup>2</sup>-propene)Ti(O-<i>i</i>-Pr)<sub>2</sub> as a Chiral Propionaldehyde Homoenolate Equivalent that Reacts with Imines with Excellent Stereoselectivity. An Efficient and Practical Access to Optically Active γ-Amino Carbonyl Compounds
作者:Sentaro Okamoto、Xin Teng、Shintaro Fujii、Yuuki Takayama、Fumie Sato
DOI:10.1021/ja004140k
日期:2001.4.1
reaction of 2 derived from (S,S)- or (R,R)-3 provided syn- and anti-5n in a ratio of 55:45 or 0:100, respectively. Meanwhile, the stereochemistry of the product in the reaction of 2 with beta-silyloxyimine 4o was controlled mainly by 2. Thus, the reaction of beta-silyloxyimine 14 with 2 derived from 1 and (R,R)-3 afforded gamma-silyloxyimine 15 with 92% diastereoselectivity, from which 4-amino-6-hydroxypentadecanal
通过旋光丙烯醛 1,2-二环己基乙缩醛 (3) 与 (eta(2)-丙烯)Ti(Oi-Pr)(2) (1) 反应原位制备的手性烯丙基钛化合物 2各种无环和环状亚胺 4 以区域特异性方式提供α-加成产物 5 作为 E-和 Z-异构体的混合物,具有良好的综合收率,其中前者占主导地位,比例为 92:8 至 >95: 5. 在几种情况下可以分离的(E)-和(Z)-5和纯(E)-5的混合物分别转化为相应的β-氨基酯6以确认绝对构型和对映体纯度。对于(E)-和(Z)-5的混合物,新形成的5的不对称中心的ee超过78%,对于纯(E)-5的超过96%。通过利用5中乙烯基醚部分的多功能性,旋光性 γ-氨基醛 8、γ-氨基醛缩醛 7 和 10、γ-氨基酸 9、β-氨基酯 6 和吡咯烷异喹啉 12 很容易制备。2与旋光α-甲硅烷氧基亚胺4n反应,观察到显着的双立体分化;因此,衍生自(S,S)-或(R,R)-3的