Iridium and a Brønsted acid cooperatively catalyzed chemodivergent and stereoselective reactions of vinyl benzoxazinones with azlactones
作者:Meng Sun、Xiao Wan、Si-Jia Zhou、Guang-Jian Mei、Feng Shi
DOI:10.1039/c8cc08962k
日期:——
Under cooperativecatalysis of iridium and a Brønsted acid, different C4-substituted azlactones react with vinyl benzoxazinones via a formal [4+2] cycloaddition or substitution reaction in a chemo- and stereoselective mode. Furthermore, the catalyticasymmetric version of the formal [4+2] cycloaddition established cooperativecatalysis of iridium and a chiral thiourea-tertiary amine.
Enantioselective iridium catalyzed α-alkylation of azlactones by a tandem asymmetric allylic alkylation/aza-Cope rearrangement
作者:Xue-Dan Bai、Qing-Feng Zhang、Ying He
DOI:10.1039/c9cc01450k
日期:——
The development of an iridium catalyzedenantioselective α-alkylation of azlactones has been described. The reaction provides rapid access to a wide range of enantio-enriched quaternary carbon center allylated 2,4-diaryloxazol-5(2H)-ones in excellent yields with high enantioselectivities. The transformation was achieved through a tandem allylicalkylation/aza-Cope rearrangement, affording the desired
Copper-Catalyzed Decarboxylative [3 + 2] Annulation of Ethynylethylene Carbonates with Azlactones: Access to γ-Butyrolactones Bearing Two Vicinal Quaternary Carbon Centers
An efficient decarboxylative [3 + 2] annulation reaction of ethynylethylene carbonates and azlactones has been developed with a copper salt as catalyst. This practical methodology gives access to a diverse library of γ-butyrolactones bearing α,β-two vicinal quaternary carbon centers in good to high yields with good levels of diastereoselectivities (up to 98% yield, >95:5 dr). Preliminary trials on
molecular sieves as an additive. The reaction conditions were suitable to 4-alkyl and benzyl-substituted azlactones as well as N-(benzyl/alkyl/arylthio)succinimides, affording adducts with high enantioselectivities (81–94% ee).