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.
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.
Tertiary and Quaternary Carbon Formation via Gallium-Catalyzed Nucleophilic Addition of Organoboronates to Cyclopropanes
作者:Truong N. Nguyen、Jeremy A. May
DOI:10.1021/acs.orglett.7b03349
日期:2018.1.5
via homoconjugate addition of organoboron nucleophiles to diester- and ketone-functionalized cyclopropanes. Electron donor group cyclopropane substituents were not needed, allowing electron-deficient aryl, alkenyl, alkyl, and hydrogen-substituted cyclopropanes to be used. The catalytic conditions were compatible with alkenyl, alkynyl, and arylnucleophiles, including ortho-substituted aromatics, to