Chiral Phosphoramide-Catalyzed Enantioselective Addition of Allylic Trichlorosilanes to Aldehydes. Preparative Studies with Bidentate Phosphorus-Based Amides
作者:Scott E. Denmark、Jiping Fu、Michael J. Lawler
DOI:10.1021/jo052203h
日期:2006.2.1
that more than one Lewis basic moiety (phosphoramide) is involved in the rate- and stereochemistry-determining step of enantioselective allylation, bidentate chiral phosphoramides were developed. Different chiral phosphoramide moieties were connected by tethers of methylene chains of varying length. The rate and enantioselectivity of allylation with allyltrichlorosilane promoted by the bidentate phosphoramides
基于机械学的见解,即对映选择性烯丙基化的速率和立体化学决定步骤涉及多个路易斯基本部分(磷酰胺),开发了二齿手性磷酰胺。通过不同长度的亚甲基链的束缚连接不同的手性磷酰胺部分。发现由二齿磷酰胺促进的与烯丙基三氯硅烷的烯丙基化的速率和对映选择性高度依赖于系链长度。设计了一种新的基于2,2'-双吡咯烷骨架的磷酰胺,在烯丙基化反应中具有良好的收率,有效的转化率和高的对映选择性。对映体纯的2,2'-双吡咯烷的合成很容易通过吡咯烷的光二聚化,然后用四氢呋喃进行拆分而大规模完成。l(或d)酒石酸。用各种取代的烯丙基三氯硅烷和不饱和醛检查了烯丙基化反应的范围。通过添加不对称的γ-二取代的烯丙基三氯硅烷,该方法已应用于立体异构的季中心的构建。