possible stereoisomers was obtained in the asymmetric cascade cyclopropanation of alkylidene oxindoles with ethyl 2‐chloroacetoacetate. Improved catalyst design ensured that spirocyclopropyl oxindoles featuring two quaternary centers were synthesized in high yield and high enantio‐ and diastereoselectivity (see scheme).
螺
环丙烷:亚烷基ide
吲哚与
2-氯乙酰乙酸乙酯的不对称级联
环丙烷化仅获得八种可能的立体异构体中的一种。改进的催化剂设计确保以高收率,高对映和非对映选择性合成具有两个季中心的螺环丙基羟
吲哚(参见方案)。