aldols from (Z)-enolates. However, for each enolate type, the diastereoface selectivities varied widely (by factors of 5–400) with the relative configuration and nature of the C5 protecting group in the 8 starting ketones. Plausible transition state models are postulated to rationalize some of these observations. The relative configurations for the complete set of 16 diastereomeric 2-(2-ethyl-1,3-
2-甲基
丙醛与6-(2-乙基-1,3-二氧杂戊环-2-基)-5的四个外消旋非对映异构体的5- O-甲氧基甲基和5- O-三乙基甲
硅烷基衍
生物的各种烯醇化物的醛醇缩合反应的非对映选择性。报道了-羟基-
4-甲基庚烷-3-酮。(E)-烯醇二环己基
硼酸酯,(Z)-烯醇9-BBN
硼酸酯(即9-(((Z)-enoxy)-9)-
硼环[3.3.1]
壬烷),Li(E)-烯酸酯的反应研究了Li(Z)-烯酸酯和Ti(IV)(Z)-烯酸酯。
硼和
锂烯醇盐是通过标准方法制备的,而Ti(IV)烯醇盐是通过与TiCl反应将Li(Z)-烯醇盐进行
金属转移而获得的n(O i -Pr) 4– n( n = 0-2)。Aldol的相对话题性(简单的非对映选择性)与烯醇的几何形状密切相关:( E)-烯醇的反羟醛和( Z)的顺醛)-烯醇。但是,对于每种烯醇盐类型,非对映体选择性随8个起始酮中C5保护基的相对构型和性质而变化很大(5到