title: Asymmetric N-Heterocyclic Carbene Catalyzed Annulation of 2-Alkenylbenzothiazoles with α-Chloro Aldehydes.
abstract: Diastereo- and enantioselective N-heterocyclic carbene catalyzed 1-azadiene Diels-Alder reactions of (E)-2-styrylbenzothiazoles with α-chloro aldehydes are reported. This annulation strategy provides an efficient access to medicinally important dihydrobenzothiazolopyridin-1-ones in good to excellent yields (44-97%) with very good to excellent stereoselectivities (up to 9:1 dr, 98% ee) and tolerates quite a range of substituents.
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: Qijian
authors.initials: Q
authors.lastname: Ni
authors.affiliation: Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany.
authors.forename: Chen
authors.initials: C
authors.lastname: Zhu
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 carbenes; annulation; asymmetric synthesis; aza-Diels–Alder reaction; organocatalysis