Starting from the conveniently available ex-chiral pool building block (R,R)-hexa-1,5-diene-3,4-diol, the ten-membered ring lactones stagonolide E and curvulide A were synthesized using a bidirectional olefin-metathesis functionalization of the terminal double bonds. Key steps are (i) a site-selective cross metathesis, (ii) a highly diastereoselective extended tethered RCM to furnish a (Z,E)-configured dienyl carboxylic acid and (iii) a Ru–lipase-catalyzed dynamic kinetic resolution to establish the desired configuration at C9. Ring closure was accomplished by macrolactonization. Curvulide A was synthesized from stagonolide E through Sharpless epoxidation.
从方便获取的外源手性池构建块(R,R)-己二烯-3,4-二醇出发,利用双向烯烃交换反应合成了十元环内酯stagonolide E和curvulide A。关键步骤包括:(i)位选择性交叉烯烃交换反应,(ii)高对映选择性的延伸挂链环烯烃闭环反应,形成(Z,E)构型的二烯基羧酸,以及(iii)Ru-脂肪酶催化的动力学拆分反应,在C9位建立所需的构型。环闭合通过大环内酯化实现。通过Sharpless环氧化反应,从stagonolide E合成了curvulide A。