Enantioselective Construction of Cyclobutanes: A New and Concise Approach to the Total Synthesis of (＋)-Piperarborenine B

摘要

A highly diastereoselective and enantioselective Cu(Ⅱ)/SaBOX-catalyzed [2 ＋ 2] cycloaddition of methylidenemalonate and multisubstituted alkenes was developed to furnish optically active cyclobutanes in high yields with ＞99/1 dr and up to ＞99% ee. By application of the newly developed method, the total synthesis of (＋)-piperarborenine B was completed in eight steps from methylidenemalonate and olefin in 17% overall yield with ＞99/1 dr and 99% ee.