(−)-pre-swinholide A were devised based on the analysis in Scheme 1. In the first route, a boron-mediated aldol reaction between the ethyl ketone 19 and the aldehyde 3 was used to construct the C15-C16 bond with moderate diastereoselectivity. In the second route, a Mukaiyama aldol reaction between the methyl ketone 54 and the aldehyde 4 introduced the C18-C19 bond with complete stereocontrol.
基于方案1中的分析,设计了两种(-)-前-硬脂醚A的偶联策略。在第一途径中,使用乙酮19和醛3之间的
硼介导的羟醛反应来构建具有中等非对映选择性的C 15 -C 16键。在第二种路线中,甲基酮54和醛4之间的Mukaiyama醛醇缩合反应引入了具有完全立体控制的C18-C 19键。