A dearomative formal (4+2)-cycloaddition reaction between 2-substituted 3-furaldehydes derivatives and isatins or α,α,α-trifluoroacetophenones as electrophiles has been established under NHC-catalysis. This approach utilizes the process of hydrogen chloride 1,4-elimination leading to a highly reactive NHC-bound heterocyclic o-QDM intermediates derived from 3-furaldehydes, which play a key role in the process. By using this strategy, a series of structurally diverse 6,7-dihydro-4H-furo[3,2-c]pyran-4-ones was prepared in 41–85% yields. In addition, the potential of the obtained (4+2)-cycloadducts has been confirmed in the synthesis of interesting class of spirooxindole derivative containing 6,7-dihydro-4H-furo[3,2-c]pyran scaffold. 

NHC‐catalyzed 1,4‐elimination in the dearomative activation of 3‐furaldehydes towards (4+2)‐cycloadditions

NHC-catalyzed N-H functionalization/cycloaddition reaction of indole aldehyde and ketone: A DFT perspective

Over the recent decades, due to the special electronic characteristics and diverse reactivities, N‐heterocyclic carbene (NHC) has received significant interest in organocatalyzed reactions. The formation of Breslow intermediates by NHC can convert into acyl anion equivalent, enolates, homoenolate, acyl azolium, and vinyl enolate etc., and the cycloaddition reactions of these species has attracted lots of attention. In this review, we focus on the summry of the development of NHC‐activation of carbonyl carbon (or imine carbon) in situ, α‐, β‐, γ‐, and beyond, and the cycloaddition reaction of these species.

Rui Deng

Papers

Carbene-Catalyzed Activation of Formyl-phenylacetic Esters for Access to Chiral Dihydroisoquinolinones.