A convergent and highly stereoselective [4+2] cycloaddition of in situ-generated ortho-Quinone methides (o-QMs) and azlactone enols has been successfully developed through a triple Brønsted acid catalysis strategy. This protocol provides an efficient and mild access to various densely functionalized dihydrocoumarins bearing adjacent quaternary and tertiary stereogenic centers in high yields with excellent diastereo- and enantioselectivity.

A sequential one-pot Cu-catalyzed asymmetric Henry reaction and iodocyclization is disclosed. The transformation provides efficient access to biologically and synthetically useful 2,2,5-trisubstituted tetrahydrofuran derivatives. The combination of Cu(OAc)₂·H₂O with a novel chiral sulfoxide–Schiff base hybrid ligand under mild reaction conditions tolerates a wide range of 4-substituted γ,δ-unsaturated aldehydes, and the subsequent iodocyclization furnishes the corresponding products in generally high yields with excellent enantioselectivities. The products can be easily converted into amines with excellent diastereo- and enantioselectivities.

An efficient halocyclization of β,γ-unsaturated hydrazones with N-bromosuccinimide was developed without the addition of any additives under mild reaction conditions to provide facile access to biologically important 4,5-dihydropyrazoles. Under the optimized conditions, a variety of highly substituted 4,5-dihydropyrazole derivatives were obtained in generally good yields. Moreover, this reaction can be further applied to the synthesis of pyrazoles in a one-pot fashion.

An organocatalytic asymmetric conjugate addition of 2-oxindole-3-carboxylate esters to 2-phthalimidoacrylates catalyzed by a quinine-derived thiourea is described. The reaction provides efficient access to a variety of quaternary oxindole based C^γ-tetrasubstituted α-amino acid derivatives in good to excellent yields (up to 96 %) with moderate to good enantioselectivity (up to 90 % ee). The opposite enantiomers of the products can also be obtained with comparable yields and stereoselectivity by simply using a quinidine-derived thiourea catalyst.

A visible-light photocatalytic generation of N-centered hydrazonyl radicals has been accomplished for the first time. This approach allows efficient intramolecular addition of hydrazonyl radical to terminal alkenes, thus providing hydroamination and oxyamination products in good yields. Importantly, the protocol involves deprotonation of an NH bond and photocatalytic oxidation to an N-centered radical, thus obviating the need to prepare photolabile amine precursors or the stoichiometric use of oxidizing reagents.

A visible-light-induced photocatalytic aerobic oxidation/[3+2] cycloaddition/aromatization cascade between secondary amines and isocyanides has been successfully developed. The reaction provides a general and efficient access to diversely substituted imidazoles and imidazo[1,5-a]quinoxalin-4(5 H)-ones in good yields under mild conditions.

A visible-light photocatalytic generation of N-centered hydrazonyl radicals has been accomplished for the first time. This approach allows efficient intramolecular addition of hydrazonyl radical to terminal alkenes, thus providing hydroamination and oxyamination products in good yields. Importantly, the protocol involves deprotonation of an NH bond and photocatalytic oxidation to an N-centered radical, thus obviating the need to prepare photolabile amine precursors or the stoichiometric use of oxidizing reagents.