An N-heterocyclic carbene (NHC)-catalyzed formal [2+4] annulation reaction of aliphatic aldehydes with oxindole-derived α,β-unsaturated ketimines under oxidative conditions is reported, affording spirocyclic oxindole δ-lactams with good yields, moderate diastereoselectivies, and good to excellent enantioselectivies. This reaction can be readily carried out on a gram scale, and the products could be further transformed to other synthetically useful compounds.

An efficient cascade reaction of 2-(1-alkynyl)-2-alken-1-ones with 2-naphthols promoted by silver trifluoroacetate is disclosed, providing an expeditious access to 1,2-dihydronaphtho­[2,1-b]­furans with moderate to good yields. This domino process involves highly regio- and diastereoselective sequential cyclization/nucleophilic addition/oxidative ring opening/oxa-Michael addition reactions to construct three new chemical bonds and one new five-membered ring. A gram-scale experiment and the preliminary results to develop an asymmetric variant are also presented to show the practicality and potential of the current reaction.

A highly efficient [8 + 2] cycloaddition reaction of azaheptafulvenes with α-chloro aliphatic aldehydes enabled by N-heterocyclic carbene catalysis is presented, delivering cis-cycloheptatriene-fused γ-lactams with good yields, moderate to good diastereoselectivies, and excellent enantioselectivies. This higher order cycloaddition reaction can be readily expanded to the gram scale, and the products could be further transformed to other useful compounds via simple operations.

A highly stereoselective Mannich reaction of α-amino acid derived azlactones with isatin-derived ketimines enabled by a chiral bifunctional squaramide organocatalyst is reported, affording α,β-diamino acid derivatives bearing vicinal quaternary stereocenters in moderate to good yields (40–95%), moderate to excellent diastereoselectivities (3:1 → 20:1), and good to excellent enantioselectivities (66–97%). This reaction can be readily performed on gram scale, and the Mannich adduct could be easily converted to the corresponding α,β-diamino ester via simple operations.

An N-heterocyclic carbene (NHC) catalyzed formal [3 + 3] cycloaddition reaction of β,β-disubstituted, α,β-unsaturated carboxylic esters with 3-amino benzofurans is doucumented, furnishing benzofuran fused δ-lactams bearing an all-carbon quaternary stereocenter...