Cu-Catalyzed Asymmetric Borylative Cyclization of Cyclohexadienone-Containing 1,6-Enynes
摘要:
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)).
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
Ligand and substrate effects during Pd-catalyzed cyclizations of alkyne-tethered cyclohexadienones
作者:Rodolfo Tello-Aburto、Kyle A. Kalstabakken、Andrew M. Harned
DOI:10.1039/c3ob27491h
日期:——
The effects of ligand and substrate choice on the Pd-catalyzed cyclization of alkyne-tethered cyclohexadienones were examined. In the presence of a chiral ligand, the enantioselectivity of the desymmetrization is remarkably sensitive to structural changes in both the ligand and the substrate. Additionally, the regioselectivity of the reaction (5- vs. 6-memberedringformation) is dependent on the proximity
Cationic Palladium(II)-Catalyzed Reductive Cyclization of Alkynyl Cyclohexadienones
作者:Weiming Wu、Tianyu Chen、Junjie Chen、Xiuling Han
DOI:10.1021/acs.joc.7b02641
日期:2018.1.19
A cationic palladium(II)-catalyzed reductive cyclization of cyclohexadienone-containing 1,6-enynes by using ethanol as a hydrogen donor and solvent was successfully developed. This procedure offers convenient access to cyclohexenone-annulated heterocycles under mild reaction conditions. The reaction was initiated by hydropalladation of the alkyne and was quenched by addition of the intramolecular conjugate