title: Regioselective α-Addition of Deconjugated Butenolides: Enantioselective Synthesis of Dihydrocoumarins.
abstract: The enantioselective α-addition of deconjugated butenolides has rarely been exploited, in contrast to the well-studied γ-addition of deconjugated butenolides. In this study, an unprecedented asymmetric α-addition/transesterification of deconjugated butenolides with ortho-quinone methides generated in situ afforded a series of functionalized 3,4-dihydrocoumarins containing two contiguous stereogenic centers with excellent diastereo- and enantioselectivity. DFT calculations suggested that the rarely observed regioselectivity was due to the distortion energy that resulted from the interaction between the nucleophilic dienolate and the electrophilic ortho-quinone methide.
authors.affiliation: State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, P.R. China.
authors.forename: Bo
authors.initials: B
authors.lastname: Wu
authors.affiliation: School of Chemistry and Chemical Engineering, Chongqing University, Chongqing, 400030, P.R. China.
authors.forename: Zhaoyuan
authors.initials: Z
authors.lastname: Yu
authors.affiliation: State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, P.R. China.
authors.forename: Xiang
authors.initials: X
authors.lastname: Gao
authors.affiliation: School of Chemistry and Chemical Engineering, Chongqing University, Chongqing, 400030, P.R. China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Lan
authors.affiliation: State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, P.R. China.
authors.forename: Yong-Gui
authors.initials: YG
authors.lastname: Zhou
keywords: asymmetric catalysis; butenolides; dihydrocoumarins; nucleophilic addition; ortho-quinone methides