Kinetic Resolution of Racemic Chromenes via Asymmetric Epoxidation: Synthesis of (+)-Teretifolione B

摘要

Kinetic resolution stands as a viable strategy for accessing chiral compounds in enantiomerically enriched form, particularly in cases where effective methods are not available for direct asymmetric synthesis from the chiral pool or from achiral precursors. In this context, the enantioselective construction of compounds that contain quaternary sterepcenters remains a difficult challenge in asymmetric synthesis. Given the remarkably high levels of enantioselectivity attainable in the (salen)Mn-catalyzed epoxidation of prochiral 2,2-dimeth-ylchromene derivatives, we evaluated whether chiral 2,2'-dialkylchromenes, which bear quaternary stereo-centers adjacent to an oxidizable olefinic moiety, might be good candidates for kinetic resolution with these catalysts. We report here the succassfui implementation of this strategy and its application to the first asymmetric synthesis of teretifolione B, the monomer component of the potent anti-HIV agent conocurvone.