Cyclopropane−Aldehyde Annulations at Quaternary Donor Sites: Stereoselective Access to Highly Substituted Tetrahydrofurans
摘要:
A diastereoselective synthesis of pentasubstituted tetrahydrofurans via a Lewis acid catalyzed (3 + 2)-annulation of quatemary donor site cyclopropanes and aldehydes is described. The reaction is catalyzed by Sn(OTf)(2), SnCl4, or Hf(OTf)(4) in yields up to 95% and diastereomeric ratios as high as 99:1.