with high stereoselectivities. Those cyclized products were subjected to ring-closing metathesis to afford the polycyclic ethers 38-42, 44, and 45 in good yields. The usefulness of the present methodology was demonstrated by the convergent synthesis of the CDEF ring system of brevetoxin B (1) and the CDEFG ring system of gambierol (2).
α-乙酰氧基醚 15-22 的
路易斯酸介导反应以良好的收率和高立体选择性得到相应的环化产物 23、25、27、29、31、32、34 和 36。将这些环化产物进行闭环复分解,以良好的收率得到多
环醚38-42、44和45。本方法的有用性通过 brevetoxin B (1) 的 CDEF 环系统和甘比尔罗 (2) 的 CDEFG 环系统的收敛合成得到证明。