title: N-Heterocyclic Carbene Catalyzed Enantioselective Annulation of Benzothiazolyl Ethyl Acetates with 2-Bromoenals.
abstract: An N-heterocyclic carbene catalyzed enantioselective [3+3] annulation of benzothiazolyl acetates with 2-bromoenals has been developed. The protocol provides a direct asymmetric synthesis of dihydro-1H-benzothiazolopyridinones in good to very good yields and medium ee values. In many cases, the virtually enantiopure heterocycles are available through a single recrystallization (99% ee).
authors.affiliation: Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany.
authors.forename: Qijian
authors.initials: Q
authors.lastname: Ni
authors.affiliation: Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany.
authors.forename: Jiawen
authors.initials: J
authors.lastname: Xiong
authors.affiliation: Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany.
authors.forename: Xiaoxiao
authors.initials: X
authors.lastname: Song
authors.affiliation: Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany.
authors.forename: Gerhard
authors.initials: G
authors.lastname: Raabe
authors.affiliation: Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany.
authors.forename: Dieter
authors.initials: D
authors.lastname: Enders
keywords: N-heterocyclic carbene; annulation; asymmetric synthesis; dihydrobenzothiazolopyridinones; organocatalysis