Kuehne M E, Li Y L, Wei C Q
Department of Chemistry, University of Vermont, Burlington 05405, USA.
J Org Chem. 2000 Oct 6;65(20):6434-40. doi: 10.1021/jo000398h.
The hexacyclic ketoester 7, derived from cyclization of racemic minovincine (6), was reduced to two C-19 epimeric alcohols 8 and 9. Stereoelectronically controlled fragmentations of corresponding O-sulfonyl derivatives provided, respectively, the hexacyclic enamine 14 and, after oxidation of the olefin 16, the pentacyclic lactam 17 with a brigehead double bond. Formation of a carbamate, introduction of a second double bond at C-16, and conjugate reductive hydroxylation at C-20, or hydrogenation, gave the title products.
由外消旋米诺长春碱（6）环化得到的六元环酮酯7被还原为两种C-19差向异构醇8和9。相应的O-磺酰基衍生物的立体电子控制碎片化反应分别得到六元环烯胺14，以及在烯烃16氧化后得到的具有桥头双键的五元环内酰胺17。形成氨基甲酸酯、在C-16引入第二个双键以及在C-20进行共轭还原羟基化反应或氢化反应，得到了标题产物。
