N-Heterocyclic Carbene-Catalyzed Enantioselective Synthesis Of Spiro-And Fused Ring Compounds

Heterocyclic compounds cantaining nitrogen or oxygen atom are privileged structural building blocks in many natural products, chemical materials and drug molecules. So the construction of these kinds of compounds is very important in organic chemistry. In the last decades, N-heterocyclic carbene (NHC) has been developed as one of the most powerful organocatalysts, which can catalyze a variety of reactions under mild conditions, especially in the synthesis of cyclic compounds. In this paper, we developped N-heterocyclic carbene-catalyzed annulation of α-chloroaldehyde and bromoenals, highly enantioselective synthesis of indenopyrones and spirocyclic oxindolo-γ-lactams.In the first part, the chiral N-heterocyclic carbene-catalyzed [4+2] annulation of chloroaldehydes and 2-benzylidene-1H-indene-1,3(2H)-diones were developed, giving the corresponding indenopyrones in good yields with high diastereoselectivities and enantioselectivities, which are pharmaceutically interesting compounds.In the second part, the chiral N-heterocyclic carbene-catalyzed [3+2] annulation of α-bromoenals with 3-aminooxindoles was developed, giving the corresponding spirocyclic oxindolo-γ-lactams in good yields with high diastereoselectivities and enantioselectivities.