The direct oxidative N-acylation reaction of primary amides with aryl/α,β-unsaturated aldehydes was achieved in the presence of azolium salt C3 and an inorganic base using 3,3′,5,5′-tetra-tert-butyldiphenoquinone as the oxidant, thus providing an efficient approach for the synthesis of three types of imide compounds including N-sulfonylcarboxamides, N-sulfinylcarboxamides, and dicarboxyimides in good yield.

A simple combination of CuI/LiOtBu/DMF enables the tandem Huisgen [3 + 2] cycloaddition/amidation reaction of terminal alkynes and sulfonyl azides to 5-sulfamide-1-(N-sulfonyl)-1,2,3-triazoles I, which can undergo an alkylation/desulfonation sequence to deliver highly substituted aminotriazoles II by one-pot or one-pot, two-step procedures.

A tandem crossover-annulation and oxygenation process of conjugated enediyne-acids and ortho-alkynylanilines was achieved by palladium–copper relay catalysis under an oxygen atmosphere, giving access to the three-component assembly of 9-acylphenanthridine compounds.

A tunable copper-catalyzed azide–alkyne cycloaddition (CuAAC)-initiated multicomponent reaction strategy for the construction of 3-functionalized indolin-2-ones is reported. Upon controlling the ring opening of four-membered O-heterocyclic intermediates, this unique method enables the divergent derivatization of N-protected isatins to give three-component (3-CR) and four-component (4-CR) adducts, respectively.

The rhodium(III)-catalyzed tunable oxidative cyclization of readily available N-tosylacrylamides and diazo compounds is presented, which offers a novel method for the selective construction of fully substituted α-pyrones and furans in a regiospecific manner by employing the acylsulfonamide group as a versatile in situ removable directing group.

A formal palladium-catalyzed aerobic bimolecular carbocyclization reaction of (Z)-hexa-1,5-diyn-3-ene scaffolds has been successfully developed for the construction of 2,6-diacylnaphthalenes, wherein copper salts play a critical role in accomplishing the oxygenative homo- and hetero-dimerization processes of readily accessible enediyne–carboxylic acids and esters, respectively. The enediyne dimerization protocol provides a flexible and regiospecific approach to a variety of functionalized naphthalenes with up to six differentiated substituents in good yields by using a directing-group-assisted coupling and decoupling strategy. Mechanistic studies indicated that the two oxygen atoms being selectively incorporated into the crossover-annulation products of enediynecarboxylic acid and ester directly originate from atmospheric molecular oxygen and H2O, respectively.

A mild three-component synthetic approach to versatile 2-amino-1,4-dihydropyridines from terminal alkynes, sulfonyl azides, and N-sulfonyl-1-aza-1,3-butadienes was successfully developed and relied on the in situ generation of metalated ynamide intermediates Ib to achieve a formal inverse electron-demand hetero-Diels–Alder reaction. Experimental results suggest that alkali metal cations (Li+ and Cs+ ions) might play a critical role to achieve the cycloaddition process.

A tandem coupling–ketooxygenation reaction of readily accessible enediyne–carboxylic compounds with inner alkynes has been developed that utilizes the PdCl2/CuBr2 catalytic system under an O2 atmosphere and assembles a class of isoindolinones and o-acylbenzoic acids. The two oxygen atoms are regioselectively incorporated into enediyne units at the 1- and 6-positions from atmospheric molecular oxygen and H2O, respectively, during the present process. This study uncovered a formal [4C + 2C] benzannulation–diketonization of enediynes and alkynes via a coupling and decoupling strategy.

By using an N-heterocyclic carbene catalyst bearing a hydroxyl moiety, the asymmetric formal (3 + 2) cyclization of aryl 3-bromoenals and isatins was achieved to produce a series of chiral spirooxindole–butenolides including an alkenyl-substituted compound, which underwent benzannulations with benzynes to form intriguing spirocyclic scaffolds.

The convergent synthesis of a class of enediyne-imides as well as their palladium-catalyzed branching cyclizations, which can be accomplished in two ways leading to a set of polysubstituted furo[2,3-b]pyridines upon using the N-tosyl carboxamide moiety as an N,O-bisnucleophile, are presented.

Two types of enolates can be formed stepwise from enolisable 1,3-dicarbonyl-substituted propene systems in the presence of catalytic amounts of 1,4-diazabicyclo[2.2.2]octane (DABCO) to accomplish a highly selective carbocyclization with β,γ-unsaturated α-keto esters, giving functionalized spiroketones with vicinal quaternary stereocenters.

An NHC-catalyzed O-selective addition of nitrosoarenes with aldehydes probably upon a dual-activation mode was developed, generating a variety of O-acyl hydroxylamines without any detectable competing amidation byproducts.

A selective synthesis of either 2H-pyran-2-ones (4) or chiral dihydropyranones (6) from the same substrates of 3-bromoenals and 1,3-dicarbonyl compounds upon oxidative N-heterocyclic carbene catalysis is presented. It is shown that the oxidative transformation of 3-bromoenals under NHC catalyst can be well controlled to proceed through two pathways, i.e., elimination of reducible β-bromide or by an external oxidant 3, allowing the selective generation two sorts of unsaturated acyl azoliums, respectively.

A quinidine-derived squaramide Ib catalyzed cyclization reaction of β-oxo aldehydes 1 and aliphatic or aromatic β,γ-unsaturated α-keto ester 2 is described. Using cyclic aldehyde substrates, this procedure provided a promising approach to a variety of spiro-3,4-dihydropyrans bearing three continuous quaternary and tertiary stereocenters in moderate to good yield with high stereoselectivities. Substituents on the nitrogen atoms of the squaramide moiety of the catalyst proved crucial to the reaction outcome. The stereochemistry of the three newly formed chiral centers (trans-selective) of the major product indicates a Micheal addition/hemiacetalization domino sequence for the present annulations.

A cinchona alkaloid-catalyzed domino Michael/hemiacetalization reaction of cyclic β-oxo aldehydes and aromatic β,γ-unsaturated α-keto esters, resulting in the formation of spiro-dihydropyran architectures in good yield with high stereoselectivity (up to 97% ee), is presented.

3-Halopropenals 1 can behave as an alternative equivalent of β-acylvinyl anions (I) in the presence of N-heterocyclic carbene precursor (IPr·HCl) and DBU to afford cyclic α,β-unsaturated carbonyl derivatives, butenolides 4 and pyrazolone 6, after cyclization with 2 and 5, respectively.

Iminoisocoumarins and α-iminopyrones are prepared via Sonogashira coupling and AgOTf-catalyzed 6-endo-digO-cyclization of the enyne−amide system in dichloroethane, in one pot or stepwise, respectively.

A novel copper(I)-catalyzed tandem addition/cycloisomerization reaction of 1-phenylsulfonylalkylidenethiiranes with terminal alkynes for the convergent assembly of 2-(α-phenylsulfonylalkyl)-thiophenes is reported, which could directly assemble various functional groups incorporated into the thiophene ring.

We have discovered thiazepine moiety-controlled regioselective skeletal rearrangements of 7-oxanorbornadiene derivatives (2, 7 and 12) with high regioselectivity and/or diastereoselectivity in the presence of Brønsted acid.

The rhodium(III)-catalyzed tunable oxidative cyclization of readily available N-tosylacrylamides and diazo compounds is presented, which offers a novel method for the selective construction of fully substituted α-pyrones and furans in a regiospecific manner by employing the acylsulfonamide group as a versatile in situ removable directing group.

Two types of enolates can be formed stepwise from enolisable 1,3-dicarbonyl-substituted propene systems in the presence of catalytic amounts of 1,4-diazabicyclo[2.2.2]octane (DABCO) to accomplish a highly selective carbocyclization with β,γ-unsaturated α-keto esters, giving functionalized spiroketones with vicinal quaternary stereocenters.

A novel copper(I)-catalyzed tandem addition/cycloisomerization reaction of 1-phenylsulfonylalkylidenethiiranes with terminal alkynes for the convergent assembly of 2-(α-phenylsulfonylalkyl)-thiophenes is reported, which could directly assemble various functional groups incorporated into the thiophene ring.

We have discovered thiazepine moiety-controlled regioselective skeletal rearrangements of 7-oxanorbornadiene derivatives (2, 7 and 12) with high regioselectivity and/or diastereoselectivity in the presence of Brønsted acid.