Qijian Ni

Asymmetric Synthesis of Pyrroloindolones by N‐Heterocyclic Carbene Catalyzed [2+3] Annulation of α‐Chloroaldehydes with Nitrovinylindoles

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.

A Branched Domino Reaction: Asymmetric Organocatalytic Two‐Component Four‐Step Synthesis of Polyfunctionalized Cyclohexene Derivatives

Traditionally, domino reactions are defined as processes of two or more bond-forming reactions, in which the subsequent transformation takes place at the functionalities obtained in the former transformation under identical reaction conditions. 2] In linear domino reactions, the progress of the former step will always affect that of the next steps (Figure 1a). Among the domino/cascade reactions, organocata-

N-Heterocyclic Carbene-Catalyzed Enantioselective Annulation of Indolin-3-ones with Bromoenals

N-Heterocyclic carbene-catalyzed reactions of indolin-3-ones with 2-bromoenals opened an asymmetric access to 3,4-dihydropyrano[3,2-b]indol-2(5 H)-ones in good yields and with good to excellent enantioselectivities. This protocol tolerates a broad substrate scope. In addition, a possible mechanism for the annulation reaction is presented.

NHC‐Catalyzed Asymmetric Synthesis of Functionalized Succinimides from Enals and α‐Ketoamides

The efficient asymmetric synthesis of highly substituted succinimides from α,β-unsaturated aldehydes and α-ketoamides via NHC-catalyzed [3+2] cycloaddition has been developed. The new scalable protocol significantly expands the utility of NHC catalysis for the synthesis of heterocycles and provides easy access to assemble a wide range of succinimides from simple starting materials.

Asymmetric N-Heterocyclic Carbene Catalyzed Annulation of 2-Alkenylbenzothiazoles with α-Chloro Aldehydes.

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.

N-Heterocyclic Carbene Catalyzed Enantioselective Annulation of Benzothiazolyl Ethyl Acetates with 2-Bromoenals.

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).