A highly diastereo- and enantioselective boron-mediated pentenylation reaction is presented. The chiral pentenylborane reagents, which are derived from pinene, undergo addition to various aldehydes to afford ethyl-substituted homoallylic alcohols in good yield and high stereoselectivity. The latter are then easily converted into the corresponding α,β-unsaturated δ-lactones using an acylation/ring-closing metathesis sequence. The relative and absolute stereochemistry is exclusively controlled by the reagent.
本文介绍了一种高度非对映选择性和对映选择性的
硼介导
戊烯化反应。从
蒎烯衍生的手性
戊烯基
硼烷试剂与各种醛反应,以良好的产率和高度的立体选择性提供乙基取代的同烯丙基醇。后者随后通过酰化/环合复分解反应序列容易地转化为相应的α,β-不饱和δ-内酯。相对和绝对立体
化学完全由试剂控制。