Organocatalytic Asymmetric Synthesis of Trifluoromethylated Tetrahydrocarbazoles by a Vinylogous Michael/Aldol Formal [4+2] Annulation
作者:Ehsan Jafari、Pankaj Chauhan、Mukesh Kumar、Xiang-Yu Chen、Sun Li、Carolina von Essen、Kari Rissanen、Dieter Enders
DOI:10.1002/ejoc.201800034
日期:2018.6.7
A new protocol for the organocatalytic asymmetric synthesis of highly functionalized tetrahydrocarbazoles has been developed based on a vinylogous Michael/aldol reaction sequence between 3‐(trifluoroacetyl)‐2‐methyl‐indoles and enals. This formal [4+2] annulation occurs by cooperative catalysis between an achiral Brønsted base and a chiral secondary amine organocatalyst to afford tetrahydrocarbazole
Access to Spirocyclic Oxindoles via N-Heterocyclic Carbene-Catalyzed Reactions of Enals and Oxindole-Derived α,β-Unsaturated Imines
作者:Kun Jiang、Bhoopendra Tiwari、Yonggui Robin Chi
DOI:10.1021/ol3008028
日期:2012.5.4
A diastereoselective access to beta-lactam fused spirocyclic oxindoles and related compounds bearing all carbon spiro centers is described. This N-heterocyclic carbene-catalyzed process employed challenging beta,beta-disubstituted alpha,beta-unsaturated imines to react with enals.