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Updated: Jul 19, 2026

Protocol for the Synthesis of Ortho-trifluoromethoxylated Aniline Derivatives
Published on: January 19, 2016
Total synthesis of (+)-alpha-onocerin in four steps via four-component coupling and tetracyclization steps
Yuan Mi1, Jürg V Schreiber, E J Corey
1Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
Abstract:
A remarkably short (four steps, 31% overall yield) enantioselective synthesis of the structurally unique C2-symmetric tetracyclic triterpene (+)-alpha-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-epoxide 4 in 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 vinyl tert-butyldimethylsilyl ethers to vinyl triflates with retention of E or Z olefinic geometry also was utilized in the synthesis of 1. A short enantioselective synthesis of a non-C2-symmetric diastereomer of 1 is also described which uses the new methodology.
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