Chiral Phosphoramide-Catalyzed Aldol Additions of Ketone Enolates. Preparative Aspects
作者:Scott E. Denmark、Robert A. Stavenger、Ken-Tsung Wong、Xiping Su
DOI:10.1021/ja984123j
日期:1999.6.1
Trichlorosilyl enolates of ketones (enoxytrichlorosilanes) were demonstrated to be highly reactive aldol addition reagents. Trichlorosilyl enolates of cyclohexanone (E-enolate) and propiophenone (Z-enolate) reacted readily at room temperature with a wide variety of aldehydes to afford aldol addition products in high yield and diastereoselectivity (E → syn, Z → anti). These reactions were shown to be
酮的三氯甲硅烷基烯醇化物(烯氧基三氯硅烷)被证明是高度反应性的羟醛加成试剂。环己酮(E-烯醇化物)和苯丙酮(Z-烯醇化物)的三氯甲硅烷基烯醇化物在室温下很容易与多种醛反应,以高产率和非对映选择性(E→syn,Z→anti)得到羟醛加成产物。这些反应被证明对催化量的手性磷酰胺的加速非常敏感。特别是,衍生自 (S,S)-芪二胺的磷酰胺不仅在加速反应方面显着有效,而且在调节非对映选择性和提供具有良好至优异对映选择性的羟醛加成产物方面也非常有效。未促进过程的非对映选择性已被解释为通过五配位、三角双锥 (tbp) 硅配合物通过船状过渡结构进行反应的结果。磷酰胺催化的反应更复杂,...