title: Asymmetric Michael addition reactions of 3-substituted benzofuran-2(3H)-ones to nitroolefins catalyzed by a bifunctional tertiary-amine thiourea.
abstract: The current work reports an organocatalytic strategy for the asymmetric catalysis of chiral benzofuran-2(3H)-ones bearing 3-position all-carbon quaternary stereocenters. Accordingly, highly enantioselective Michael addition reactions of 3-substituted benzofuran-2(3H)-ones to nitroolefins have been developed by utilizing a bifunctional tertiary-amine thiourea catalyst. The reactions accommodate a number of nitroolefins and 3-substituted benzofuran-2(3H)-ones to give the desired chiral benzofuran-2(3H)-one products with moderate to excellent yields (up to 98%) and moderate to very good selectivities (up to 19 : 1 dr and up to 91% ee). Theoretical calculations using the DFT method on the origin of the stereoselectivity were conducted. The effect of the nitroolefin substituent position on the stereoselectivity of the Michael addition reaction was also theoretically rationalized.
authors.affiliation: State Key Laboratory of Elemento-organic Chemistry and Department of Chemistry, Nankai University, Tianjin, 300071, China. xin_li@nankai.edu.cn
authors.forename: Xin
authors.initials: X
authors.lastname: Li
authors.forename: Xiao-Song
authors.initials: XS
authors.lastname: Xue
authors.forename: Cong
authors.initials: C
authors.lastname: Liu
authors.forename: Bin
authors.initials: B
authors.lastname: Wang
authors.forename: Bo-Xuan
authors.initials: BX
authors.lastname: Tan
authors.forename: Jia-Lu
authors.initials: JL
authors.lastname: Jin
authors.forename: Yue-Yan
authors.initials: YY
authors.lastname: Zhang
authors.forename: Nan
authors.initials: N
authors.lastname: Dong
authors.forename: Jin-Pei
authors.initials: JP
authors.lastname: Cheng
mesh_terms: D000475:Alkenes / Q000138:chemical synthesis* / Q000737:chemistry; D000588:Amines / Q000737:chemistry*; D001572:Benzofurans / Q000737:chemistry*; D002384:Catalysis; D013890:Thiourea / Q000031:analogs & derivatives / Q000737:chemistry*
chemical_list: D000475:Alkenes; D000588:Amines; D001572:Benzofurans; D013890:Thiourea