title: Enantioselective Synthesis of 4H-Pyran via Amine-Catalyzed Formal (3 + 3) Annulation of δ-Acetoxy Allenoate.
abstract: The formal (3 + 3) annulations of δ-acetoxy allenoates and 1C,3O-bisnucleophiles are reported with the use of 6'-deoxy-6'-perfluorobenzamido-quinine (4g) as a catalyst, which provide rapid access to 4H-pyrans with excellent enantioselectivity. The reaction features a wide reaction scope and mild reaction conditions. The crucial roles of amide NH of 4g as a H-bond donor have also been elucidated, which not only activates allenoate to facilitate formation of cationic intermediate A but also enhances the electrophilicity of its δ-position for nucleophilic 1,6-addition.
authors.affiliation: Shanghai Key Laboratory of Functional Materials Chemistry, East China University of Science and Technology , 130 Meilong Road, Shanghai, 200237, China.
authors.forename: Weiping
authors.initials: W
authors.lastname: Zhou
authors.affiliation: Jiangsu Key Laboratory of Advanced Catalytic Materials & Technology, School of Petrochemical Engineering, Changzhou University , 1 Gehu Road, Changzhou, 213164, China.
authors.forename: Chunjie
authors.initials: C
authors.lastname: Ni
authors.affiliation: Jiangsu Key Laboratory of Advanced Catalytic Materials & Technology, School of Petrochemical Engineering, Changzhou University , 1 Gehu Road, Changzhou, 213164, China.
authors.forename: Jiangfei
authors.initials: J
authors.lastname: Chen
authors.affiliation: Jiangsu Key Laboratory of Advanced Catalytic Materials & Technology, School of Petrochemical Engineering, Changzhou University , 1 Gehu Road, Changzhou, 213164, China.
authors.forename: Dong
authors.initials: D
authors.lastname: Wang
authors.affiliation: Shanghai Key Laboratory of Functional Materials Chemistry, East China University of Science and Technology , 130 Meilong Road, Shanghai, 200237, China.|Jiangsu Key Laboratory of Advanced Catalytic Materials & Technology, School of Petrochemical Engineering, Changzhou University , 1 Gehu Road, Changzhou, 213164, China.
authors.forename: Xiaofeng
authors.identifier: 0000-0002-6789-1691
authors.initials: X
authors.lastname: Tong