Formation of chiral tertiary homoallylic alcohols via Evans aldol reaction or enzymatic resolution and their influence on the Sharpless asymmetric dihydroxylation
作者:Matthias Theurer、Peter Fischer、Angelika Baro、Giang Son Nguyen、Robert Kourist、Uwe Bornscheuer、Sabine Laschat
DOI:10.1016/j.tet.2010.03.048
日期:2010.5
Enantioenriched tertiary homoallylic alcohol derivatives (S)-2c and (S)-2a were obtained via Evans aldol methodology and enzymatic resolution of racemic tertiary acetate 2e, respectively. In order to study asymmetric 1,3-induction of the stereogenic center present in 2, congener (R)-2a as well as its O-protected derivatives (R)-2b–d were submitted to Sharpless asymmetric dihydroxylation to yield the
对映体富集的叔高烯丙基醇衍生物(小号) - 2C和(小号) -图2a是经由埃文斯羟醛方法论和外消旋叔乙酸的酶拆分获得2E分别。为了研究该立体中心的存在不对称1,3-诱导2,同类([R )-图2a以及其直径: -保护的衍生物([R )- 2B - d被提交给Sharpless不对称二羟基化,得到非对映体1 ,2,4-三醇衍生物(2 R,4 R)-和(2 S,4 R)-3a – d,表明底物和Sharpless催化剂均未施加任何立体控制。对于较小体积的炔基取代的衍生物12b进行了类似的观察。然而,通过使用定向二羟基化,抗产物(2 R,4 R)-3a是有利的。