Palladium-mediated asymmetric synthesis of 3β,5β,7β-trihydroxycycloheptene derivatives
作者:Hiroki Yoshizaki、Kumiko Yoshioka、Yoshihiro Sato、Miwako Mori
DOI:10.1016/s0040-4020(97)00238-x
日期:1997.4
Asymmetric alkylation of 3,5,7-trihydroxycycloheptene derivative 15 was developed using a palladium catalyst with a chiral ligand. The reaction site of π-allylpalladium complex 18 is controlled by steric repulsion between the nucleophile and the substituents on the cycloheptene ring. When 15b was reacted with lithium dimethyl malonate using a catalytic amount of [Pd(C3H5)Cl]2 in the presence of (S)-BINAPO
使用具有手性配体的钯催化剂开发了3,5,7-三羟基环庚烯衍生物15的不对称烷基化。π-烯丙基铝配合物18的反应位点通过亲核体与环庚烯环上的取代基之间的空间排斥来控制。当15b与催化量的[Pd(C 3 H 5)Cl] 2在THF中的(S)-BINAPO存在下与二甲基丙二酸锂反应时,得到烷基化产物17,产率为71%,ee为42%。然而,该反应15B具有大的亲核试剂,二乙基2-锂-2-(2-丙烯基)丙二酸二乙酯,在[钯的存在(C 3H 4)Cl] 2和(S)-BINAP的THF溶液以41%的收率和94%的ee得到烷基化产物21d。以类似的方式,15b与2-(3-丁烯基)-2-硫代丙二酸二甲酯5e的反应以64%的收率和82%的ee得到21e。