Phosphine‐Catalyzed β,γ‐Umpolung Domino Reaction of Allenic Esters: Facile Synthesis of Tetrahydrobenzofuranones Bearing a Chiral Tetrasubstituted Stereogenic Carbon Center
enantio‐, diastereo‐, regio‐, and chemoselective phosphine‐catalyzedβ,γ‐umpolungdominoreaction of allenicesters with dienones has been developed for the first time. The designed sequence, involving oxy‐Michael and Rauhut–Currier reactions, produced highly functionalized tetrahydrobenzofuranones, bearing a chiraltetrasubstitutedstereogeniccenter, in up to 96 % ee.
Cu-Catalyzed Asymmetric Borylative Cyclization of Cyclohexadienone-Containing 1,6-Enynes
作者:Ping Liu、Yuki Fukui、Ping Tian、Zhi-Tao He、Cai-Yun Sun、Nuo-Yi Wu、Guo-Qiang Lin
DOI:10.1021/ja404593c
日期:2013.8.14
The first Cu-catalyzed asymmetric borylative cyclization of cyclohexadienone-containing 1,6-enynes is achieved through a tandem process: selective beta-borylation of propargylic ether and subsequent conjugate addition to cyclohexadienone. The reaction proceeds with excellent regioselectivity and enantioselectivity to afford an optically pure cis-hydrobenzofuran framework bearing alkenylboronate and enone substructures. Furthermore, the resulting bicyclic products could be converted to bridged and tricyclic ring structures. This method extends the realm of Cu-catalyzed asymmetric tandem reactions using bis(pinacolato)diboron (B(2)pin(2)).