The direct asymmetricallylicalkylation of β,γ-butenolides with MBHcarbonates to access γ,γ-disubstituted butenolides containing adjacent quaternary and tertiary chiral centers has been presented in excellent stereoselectivities (86−96% ee, dr >95:5) and moderate to good yield (50−83%). Their synthetic utility has been well demonstrated by the facile construction of bicyclic lactones bearing 4−5
Highly enantioselective direct allylic alkylation of butenolides with Morita–Baylis–Hillman carbonates catalyzed by chiral squaramide-phosphine
作者:Tian-Chen Kang、Xuan Zhao、Feng Sha、Xin-Yan Wu
DOI:10.1039/c5ra14667d
日期:——
An efficient asymmetric vinylogous allylic alkylation of β,γ-butenolides with Morita–Baylis–Hillman carbonates has been developed. With a chiral cyclohexane-based squaramide-phosphine catalyst 5e, optically active γ,γ-disubstituted butenolides containing adjacent quaternary and tertiary chiral centers have been constructed in good-to-excellent yields (up to 98%) and excellent stereoselectivities (87 : 13–99 : 1