The catalytic intramolecular and intermolecular α-amidoalkylation of deactivated N,O-acetals equipped with either two ester groups or both an ester and a cyano groups α to the reactive center has been developed. Reactions in the cyano ester series proceeded under harsher reaction conditions than those in the diester series, but furnished products with two contiguous quaternary and tertiary stereocenters with high to complete diastereocontrol. The reactivity trends and stereoselectivity profiles exhibited by these reactions may be consistent with a relay mode exerted by the ester arm(s), which might possibly direct the catalyst delivery and/or stabilize the raising carbenium ion through anchimeric bridging.
已经开发出一种催化的分子内和分子间α-
氨基烷基化反应,该反应适用于被两个酯基或一个酯基和一个
氰基作为反应中心α-位的去活性化N,O-
缩醛。
氰酯系列的反应在更苛刻的反应条件下进行,而二酯系列则在温和条件下进行,但可以获得具有两个相邻的四元和三元立体中心,并且具有高到完全的非对映体选择性。这些反应表现出的反应活性趋势和立体选择性特征可能与酯臂施加的中继模式一致,这可能指引催化剂的输送和/或通过锚协桥稳定上升的碳正离子。