Total synthesis of (+)-α-onocerin in four steps via four-component coupling and tetracyclization steps
Total synthesis of (+)-α-onocerin in four steps via four-component coupling and tetracyclization steps
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DOI：
10.1021/ja027373f
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发表时间：
2002-09-25
影响因子：
15
通讯作者：
Corey, EJ
中科院分区：
文献类型：
--
作者：
Mi, Y;Schreiber, JV;Corey, EJ
A remarkably short (four steps, 31% overall yield) enantioselective synthesis of the structurally uniqueC2-symmetric tetracyclic triterpene (+)-α-onocerin (1) has been developed. The brevity of this mechanism depends on the assembly of four fragments (two molecules of a chiral epoxy ketone and two molecules of vinyllithium) to generate the chiral bis-epoxide4in one step, and on the efficient formation of all four carbocyclic rings in one step by cation−olefin tetracyclization. New and general methodology for the conversion of vinyltert-butyldimethylsilyl ethers to vinyl triflates with retention ofEorZolefinic geometry also was utilized in the synthesis of1. A short enantioselective synthesis of a non-C2-symmetric diastereomer of1is also described which uses the new methodology.
