title: Highly enantioselective synthesis of γ-substituted butenolides via the vinylogous Mukaiyama-Michael reaction catalyzed by a chiral scandium(III)-N,N'-dioxide complex.
abstract: A highly efficient catalytic asymmetric vinylogous Mukaiyama-Michael reaction of the 2-silyloxyfuran with chalcone derivatives, catalyzed by a chiral N,N'-dioxide-scandium(III) complex, has been accomplished which tolerates a wide range of substrates. The reaction proceeds with complete regioselectivities, excellent diastereoselectivities (up to >99 : 1 dr) and good to excellent enantioselectivities (up to 94% ee) under mild conditions, delivering highly functionalized enantiomerically enriched anti-γ-substituted butenolides. The process is air-tolerant and easily manipulated with available reagents. In order to illustrate the synthetic potential of this reaction, the gram-scale synthesis and the elaboration of the butenolides have been explored. On the basis of the experimental results, a possible catalytic cycle and favorable stereorecognition model have been proposed.
authors.affiliation: Key Laboratory of Green Chemistry & Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu, China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Zhang
authors.forename: Xiao
authors.initials: X
authors.lastname: Xiao
authors.forename: Lili
authors.initials: L
authors.lastname: Lin
authors.forename: Xiaohua
authors.initials: X
authors.lastname: Liu
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Feng
mesh_terms: D015107:4-Butyrolactone / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry; D002384:Catalysis; D002599:Chalcone / Q000737:chemistry; D005663:Furans / Q000737:chemistry; D010087:Oxides / Q000737:chemistry; D012538:Scandium / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D005663:Furans; D010087:Oxides; D002599:Chalcone; C004511:butenolide; D015107:4-Butyrolactone; D012538:Scandium