Palladium Enolate Umpolung: Cyclative Diacetoxylation of Alkynyl Cyclohexadienones Promoted by a Pd/SPRIX Catalyst
作者:Kazuhiro Takenaka、Suman C. Mohanta、Hiroaki Sasai
DOI:10.1002/anie.201311172
日期:2014.4.25
A novel palladium‐catalyzed reaction involving an unusual nucleophilic attack on a palladiumenolate was developed using a spiro‐bis(isoxazoline) (SPRIX) ligand. Treatment of alkynylcyclohexadienone substrates with a Pd/SPRIXcatalyst in acetic acid under an oxygen atmosphere furnished diacetoxylated benzofuranone derivatives in good yields. This cyclativediacetoxylation proceeded enantioselectively
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)).