Hughes R C, Dvorak C A, Meyers A I
Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, USA.
J Org Chem. 2001 Aug 10;66(16):5545-51. doi: 10.1021/jo010439p.
A general route to enantiopure spirocarbocycles is described. The use of various chiral bicyclic lactams 1 that have been doubly alkylated with olefinic halides gives good yields of alpha,alpha-disubstituted chiral lactams 2 which were cyclized to spiro-olefins using ring closure metathesis methodology (Grubbs' catalyst). These spirolactams 3, formed in generally excellent yields, were shown to be smoothly transformed into spirocyclopentenone 6, spirocyclohexenone, 7, and spirolactams 8. Further demonstration of this spirocyclization methodology was featured in a formal synthesis of zizaene, by preparing in enantiomeric form the Coates' intermediate 21. This synthetic effort provided additional examples of the synthetic versatility of chiral bicyclic lactams 2a,b.
描述了一种制备对映体纯螺环碳环化合物的通用方法。使用已被烯烃卤化物双烷基化的各种手性双环内酰胺1，能以良好的产率得到α,α-二取代手性内酰胺2，使用闭环复分解方法（格拉布催化剂）将其环化生成螺烯烃。这些通常以优异产率形成的螺内酰胺3被证明能顺利转化为螺环戊烯酮6、螺环己烯酮7和螺内酰胺8。通过对映体形式制备科茨中间体21，这种螺环化方法在紫穗槐烯的形式合成中得到了进一步证明。这项合成工作提供了手性双环内酰胺2a,b合成多功能性的更多实例。
