title: Asymmetric synthesis of pyrroloindolones by N-heterocyclic carbene catalyzed [2+3] annulation of α-chloroaldehydes with nitrovinylindoles.
abstract: NHC-enolate plus 3: N-heterocyclic carbenes (NHCs) serve as organocatalysts for the [2+3] annulation of nitrovinylindoles with α-chloroaldehydes via an intermediate azolium enolate. The method provides trans-disubstituted pyrroloindolones with good yields and excellent diastereo- and enantioselectivities. Further transformations lead to tetracyclic pyrrolo[1,2-a]indoles with potential psychotropic and other bioactivities.
authors.affiliation: Institut für Organische Chemie, RWTH Aachen University, Landoltweg 1, 52074 Aachen (Germany).
authors.forename: Qijian
authors.initials: Q
authors.lastname: Ni
authors.forename: Huan
authors.initials: H
authors.lastname: Zhang
authors.forename: André
authors.initials: A
authors.lastname: Grossmann
authors.forename: Charles C J
authors.initials: CC
authors.lastname: Loh
authors.forename: Carina
authors.initials: C
authors.lastname: Merkens
authors.forename: Dieter
authors.initials: D
authors.lastname: Enders
keywords: N-heterocyclic carbenes; annulation; asymmetric synthesis; indole derivatives; organocatalysis