•A metal-free P–N cross-coupling is developed.•Halogen bonding activation by DBU is the driving force for the P–N cross-coupling.•An ionic rather than a radical mechanism is proposed.•N-Haloimides can be utilized as an aminating reagent.We have demonstrated that N-haloimides can be utilized as an aminating reagent, in addition to the traditional brominating reagent. Herein, the P–N cross-coupling of P(O)–H compounds and N-bromophthalimide has been developed with the DBU activation strategy. The nitrogen source may arise from internal N-bromophthalimide itself (a self-immolating reagent) or external phthalimide derivatives (with NBS-DBU activation system). The reaction features broad phosphorous compounds scope, including H-phosphinates, H-phosphonates, and H-phosphine oxides, and short reaction time (less than 10 min). This method provides a simple, convenient, efficient, and green route toward phosphoramidates which are of biological importance under mild conditions.

When DBU is added, the cross-coupling reaction between alkyl halides (halogen = Cl, Br and I) and N-haloimides (halogen = Cl, Br) occurs, resulting in the formation of aminated products. A halogen bond activated nucleophilic substitution mechanism was proposed. The methodology represents an elegant example of applying the halogen bond activation strategy in an organic transformation.

Activated by DBU, N-haloimides can be used as both halogen and nitrogen sources to achieve the difunctionalization of terminal alkynes, giving rise to useful halogenated enamines with high efficiency and high regio- and stereoselectivities. The cascade reaction features simple manipulation, mild conditions, a broad substrate scope, readily available reagents, and atom-economy.

Efficient synthesis of spiro[isoquinolinone-4,2′-oxiranes] was achieved based on a multicomponent one-pot reaction of readily available cis-2-acetyl-oxirane-2-carboxamides, arylaldehydes and malononitrile at room temperature. However, in the reaction with trans-2-acetyl-oxirane-2-carboxamide substrates, 3-iminoisoindolinones were obtained in moderate to high yields.

A novel and efficient method for the construction of γ-lactams with an all-carbon quaternary center is developed via a DABCO-catalyzed reaction of EWG-activated cyclopropanecarboxamides and electron-deficient alkenes. The process involves sequential ring-opening of activated cyclopropanes, intermolecular Michael addition and intramolecular aza-cyclization.

Hypervalent iodine(III)-mediated dioxygenation and diamination of alkenes have been previously developed. In this study, the potential application of hypervalent iodine(III) reagent was successfully extended to the dialkylation and cyclopropa(e)nation of unsaturated alkenes and alkynes. The reactions of alkenes with malononitrile and other active methylene compounds as the carbon nucleophiles give access to multisubstituted cyclopropane derivatives in moderate to excellent yields. Both electron-rich and electron-deficient alkenes are suitable substrates. Alkynes, no matter terminal or internal alkynes, work well, affording the corresponding highly functionalized cyclopropenes efficiently. A plausible mechanism of iodo(III)cyclopropanation, ring opening attack by the carbon-nucleophile, and recyclization was proposed for the cyclopropanation of trans-alkene substrates. The cyclopropenation was thought to proceed via iodo(III)cyclopropanation, ring-opening attack by the carbon-nucleophile, recyclization into a four-membered iodo(III)cyclobutene and final reductive elimination. The protocol might provide a complementary route to cyclopropanation/cyclopropenation.

An efficient synthesis of γ-ketoamides was developed by the one-pot multicomponent reaction of chalcones, malononitrile and DMF (as both the reactant and solvent) in the presence of NaOH (3.0 equiv.). The reaction features high atom economy, easily available starting materials, operational simplicity, and good tolerance with diverse functional groups.

By DBU activation, N-haloimides may act as a self-immolating reagent, to convert β-dicarbonyl compounds into α-imidated products in high efficiency. The DBU/N-haloimide protocol provides a novel, mild, and complimentary access to α-imidated β-dicarbonyl compounds, without the necessity of external nitrogen sources.

Allylic amination reactions of alkenes, with an NBP (N-bromophthalimide) or NBS (N-bromosuccinimide)/DBU combination, were developed, in which both internal and external nitrogen nucleophiles can be installed directly. Dual activation of NBS or NBP by DBU leads to more electrophilic bromine and more nucleophilic nitrogen atoms simultaneously. This protocol may provide a novel and complementary access to allylic amination under mild conditions.

A DABCO-mediated organocatalyzed anion relay cascade based on 1-cinnamoylcyclopropanecarboxamides has been developed and applied in the construction of 2,3-dihydrofurans with the original alkene and amide functionalities intact. In the aza-oxy-carbanion relay process, DABCO provides both the electron source and sink. The enolate anion-triggered ring opening of the cyclopropane is ascribed to the key step in the anion relay cascade.

A one-pot cascade transformation of chalcones into β-imidoketones has been developed, in which NBS provides both electrophilic bromine and nucleophilic nitrogen sources, and DBU functions as a nucleophilic reagent to activate NBS to be a more electrophilic bromine species and to further remove the bromine of α-bromoketones. The whole process involves tandem bromoamination and debromination, which represents a unique example of preparing β-aminoketones by the reaction of chalcones with the NBS/DBU combination.

The introduction of polyoxometalates (POMs) into the metal–organic complex synthetic system containing copper ions and bichelate-bridging ligands (bis(3-(2-pyridyl)pyrazole-1-ylmethyl)benzene, bppmb) led to the isolation of three new organic–inorganic hybrid compounds [CuIILo]2H[BW12O40]·4H2O (1), [CuILo]4[SiW12O40]·5H2O (2), and [CuLp]3H2[BW12O40]·5H2O (3) (Lo = 1,2-bppmb and Lp = 1,4-bppmb). All three compounds were hydrothermally synthesized and characterized by elemental analyses, IR spectra, TG analyses, powder X-ray diffraction, and single-crystal X-ray diffraction analyses. In these compounds, the use of Keggin-type POMs induces the formation of a series of new metal–organic secondary building units based on the copper ions and bppmb ligands such as helical chain and chiral Möbius Strip, which further form interesting supramolecular self-assemblies with the polyoxoanions. The degradation of Rhodamine-B (RhB) under UV irradiation with compounds 1–3 as the heterogeneous photocatalysts was investigated, and these compounds show good photocatalytic properties for RhB degradation.

NBS-mediated addition–elimination reaction of sulfonamides/carboxamides and formamides afforded N-sulfonylamidines and N-formylarylamides, respectively, depending on the different mechanism of elimination. Hydrogen bond-induced proton transfer leads to enhanced reactivities and was proposed as the key driving force for the reaction to take place. The protocol demonstrates the possibility of constructing chemical bonds based on a proton transfer strategy induced by noncovalent hydrogen bond interaction.

The reaction of 1-alkenoylcyclopropane carboxylic acids with NBS or NIS was investigated, which provides an efficient route to biologically important 7-halogenated furo[3,2-c]pyran-4-ones in a one-pot transformation. The major pathway for the formation of the O–O heterocycles was proposed as a halo-oxa-cyclization, HBr elimination, cyclopropane ring-opening and recyclization (intramolecular oxa-cyclization), and bromination cascade. The double-oxa-cyclization represents a novel synthetic strategy towards functionalized furo[3,2-c]pyranones.

A mild, efficient and practical method for the preparation of dihalogenated products has been developed. Benzoic acid (0.2 equiv.) is capable of catalyzing the reactions of unsaturated carbonyl compounds with N-halosuccinimides (NXS, X = Br and Cl) to afford a series of dihalogenated products at room temperature.

New zinc phthalocyanine, peripherally functionalized with eight electron-withdrawing benzothiadiazole moieties through alkynic bond linkage, has been designed and synthesized. It was found that DBU acts as a ligand to coordinate with the central zinc ion at the axial direction. By this strategy, not only broad absorption covering the range of 300 ~ 900 nm, but also good solubility in common organic solvents and amorphous stability were achieved, making it an attractive candidate for potential application in solution processed small molecule-based organic photovoltaic devices.

Cyanation of α,β-unsaturated enones by employing malononitrile as the organic cyanation source has been disclosed, which proceeds efficiently at room temperature in open air under metal-catalyst-free conditions.

Highly efficient C–O bond formation has been developed via carboxylic acid catalyzed reaction of 1-acetylcyclopropanecarboxamides with N-halosuccinimide (NXS), which provides strategically novel and atom-economic access to biologically important 5-amino-3(2H)-furanones. The mechanism of halonium-initiated tandem oxa-cyclization and ring opening of cyclopropane was proposed. A variety of nucleophiles were found to open the cyclopropane.

A one-pot cascade transformation of ketones into α-imidoketones has been developed, in which N-bromosuccinimide (NBS) provides both electrophilic bromine and nucleophilic nitrogen sources, and diazabicyclo[5.4.1]undec-7-ene (DBU) functions as a base and a nucleophilic promoter for the activation of NBS. α-Bromination is supposed as the key step in the process, which takes place between more electrophilic bromide active species and enolates.

A highly efficient multi-component anion relay cascade reaction based on 1-acetylcyclopropanecarboxamides, aldehydes and acrylonitrile has been developed, which provides strategically novel and atom-economic access to biologically important biscyanoethylated furo[3,2-c]pyridinones. In this one-pot transformation, up to five bonds (one C–N, one C–O and three C–C bonds) were constructed.

A simple, efficient and practical copper-catalyzed aerobic oxidative synthesis of α-ketoamides from aryl methyl ketones, aliphatic amines and N-iodosuccinimide (NIS) has been developed. The one-pot reaction may proceed smoothly at room temperature in the open air. The possible mechanism for the formation of α-ketoamides was proposed. Molecular oxygen in air functions as both an oxidant and an oxygen source.

An aza−oxy−carbanion relay via tandem Michael addition/ring opening of cyclopropane and recyclization/carbanion migration/electrophile trapping has been developed by the utilization of 1-cinnamoylcyclopropanecarboxamides to react with various electrophiles. This represents the first example of anion relay chemistry via non-Brook rearrangement. This novel protocol has been applied in the facile and efficient synthesis of biologically active bicyclic furo[3,2-c]pyridinone compounds.

With a FeSO4/TBHP system in water, direct oxidation of sp3 C−H bonds adjacent to nitrogen of arylureas to give both unprecedented tert-butoxylated and hydroxylated products 2 was revealed. Under elevated temperatures, either 2-oxo-N-arylpyrrolidine-1-carboxamides 3 or 1,3-diarylureas 4 were attained, depending on the aliphatic ring size of the arylurea substrates.

Halonium-initiated cascade reaction of 1-alkenoylcyclopropane carboxamides was developed, which leads to the production of dihydrofuropyridinones and 3(2H)-furanones, respectively, depending on the property of substituents on the enone moiety.

Low-bandgap poly(2,7-carbazole) derivatives with variable N-substituent of ethyl (PEtCzBT), phenyl (PPhCzBT) and 4-diphenylaminophenyl (PTPACzBT) on the carbazoles, were synthesized through Suzuki coupling reaction. The polymers show excellent solubility in organic solvents (readily soluble in chloroform, THF and toluene etc.), good thermal stability (5% weight loss temperature of more than 417 °C), and electrochemical properties (reversible redox process with narrow bandgap), and deep HOMO energy levels (∼5.1 eV), allowing them promising candidates in the solar cell fabrication. Bulk-heterojunction solar cells with these polymers as electron donor and (6,6)-phenyl-C71-butyric acid methyl ester (PC71BM) as electron acceptor exhibit high Voc (0.91–0.95 V) and good power conversion efficiency (PCE) of 1.69% for PEtCzTB, 2.01% for PPhCzTB, and 2.42% for PTPACzTB.

A general and practical method for the preparation of unsymmetrically substituted ureas has been developed. By the reactions of acetoacetanilides with various amines including primary/secondary amines, a series of substituted aryl ureas were achieved in high yields. Acetoacetanilide substrates can be considered as masked reagents that liberate reactive isocyanates in situ.

Three novel low-bandgap (LGB) conjugated polythiophenes (PThBTDmCzn) incorporating separate and content-tunable benzothiadiazole and carbazole moieties have been designed and synthesized for application in bulk heterojunction polymer solar cells (PSCs). The absorption spectral, thermal, electrochemical and photovoltaic properties of the random copolymers were investigated. Broad absorption from a single polymer covering the visible region from 300 to 800 nm was observed, which was ideal for highly efficient harvesting of the solar spectrum. DSC analysis showed that the polymers readily crystallized, indicating highly ordered intermolecular packing, which is beneficial for efficient charge-carrier transport. Electrochemical studies indicate desirable HOMO/LUMO levels that enable a high open-circuit voltage while blending them with fullerene derivatives as electron acceptors. Polymer solar cells using 1:1 or 1:2 wt/wt polymer: PC61BM (methanofullerene [6,6-phenyl C61-butyric acid methyl ester] blends as the photoactive layers were fabricated and characterized. The preliminary investigation on the photovoltaic device of the PThBTDmCzn polymers gave similar power conversion efficiency of 1.1–1.2% with Voc of 0.64–0.68 V under simulated solar light AM 1.5 G (100 mW/cm2).

A domino reaction based on arylaldehydes and 1-acetylcyclopropanecarboxamides has been developed, which allows one-pot and efficient synthesis of structurally complex piperidine-2,4-diones with multiple functionalities under mild conditions. The overall transformation involves tandem aldol/intramolecular aza-Michael/(aldol)/Michael sequences.

An efficient synthesis of fully substituted pyridin-2(1H)-ones was developed via three-component one-pot reactions of readily available 1-acetyl-1-carbamoyl cyclopropanes, malononitrile and cyclic secondary amines.

Activated by DBU, N-haloimides can be used as both halogen and nitrogen sources to achieve the difunctionalization of terminal alkynes, giving rise to useful halogenated enamines with high efficiency and high regio- and stereoselectivities. The cascade reaction features simple manipulation, mild conditions, a broad substrate scope, readily available reagents, and atom-economy.

Efficient synthesis of spiro[isoquinolinone-4,2′-oxiranes] was achieved based on a multicomponent one-pot reaction of readily available cis-2-acetyl-oxirane-2-carboxamides, arylaldehydes and malononitrile at room temperature. However, in the reaction with trans-2-acetyl-oxirane-2-carboxamide substrates, 3-iminoisoindolinones were obtained in moderate to high yields.

A novel and efficient method for the construction of γ-lactams with an all-carbon quaternary center is developed via a DABCO-catalyzed reaction of EWG-activated cyclopropanecarboxamides and electron-deficient alkenes. The process involves sequential ring-opening of activated cyclopropanes, intermolecular Michael addition and intramolecular aza-cyclization.

Cyanation of α,β-unsaturated enones by employing malononitrile as the organic cyanation source has been disclosed, which proceeds efficiently at room temperature in open air under metal-catalyst-free conditions.

Halonium-initiated cascade reaction of 1-alkenoylcyclopropane carboxamides was developed, which leads to the production of dihydrofuropyridinones and 3(2H)-furanones, respectively, depending on the property of substituents on the enone moiety.

An efficient synthesis of fully substituted pyridin-2(1H)-ones was developed via three-component one-pot reactions of readily available 1-acetyl-1-carbamoyl cyclopropanes, malononitrile and cyclic secondary amines.

Hypervalent iodine(III)-mediated dioxygenation and diamination of alkenes have been previously developed. In this study, the potential application of hypervalent iodine(III) reagent was successfully extended to the dialkylation and cyclopropa(e)nation of unsaturated alkenes and alkynes. The reactions of alkenes with malononitrile and other active methylene compounds as the carbon nucleophiles give access to multisubstituted cyclopropane derivatives in moderate to excellent yields. Both electron-rich and electron-deficient alkenes are suitable substrates. Alkynes, no matter terminal or internal alkynes, work well, affording the corresponding highly functionalized cyclopropenes efficiently. A plausible mechanism of iodo(III)cyclopropanation, ring opening attack by the carbon-nucleophile, and recyclization was proposed for the cyclopropanation of trans-alkene substrates. The cyclopropenation was thought to proceed via iodo(III)cyclopropanation, ring-opening attack by the carbon-nucleophile, recyclization into a four-membered iodo(III)cyclobutene and final reductive elimination. The protocol might provide a complementary route to cyclopropanation/cyclopropenation.

An efficient synthesis of γ-ketoamides was developed by the one-pot multicomponent reaction of chalcones, malononitrile and DMF (as both the reactant and solvent) in the presence of NaOH (3.0 equiv.). The reaction features high atom economy, easily available starting materials, operational simplicity, and good tolerance with diverse functional groups.

NBS-mediated addition–elimination reaction of sulfonamides/carboxamides and formamides afforded N-sulfonylamidines and N-formylarylamides, respectively, depending on the different mechanism of elimination. Hydrogen bond-induced proton transfer leads to enhanced reactivities and was proposed as the key driving force for the reaction to take place. The protocol demonstrates the possibility of constructing chemical bonds based on a proton transfer strategy induced by noncovalent hydrogen bond interaction.

The reaction of 1-alkenoylcyclopropane carboxylic acids with NBS or NIS was investigated, which provides an efficient route to biologically important 7-halogenated furo[3,2-c]pyran-4-ones in a one-pot transformation. The major pathway for the formation of the O–O heterocycles was proposed as a halo-oxa-cyclization, HBr elimination, cyclopropane ring-opening and recyclization (intramolecular oxa-cyclization), and bromination cascade. The double-oxa-cyclization represents a novel synthetic strategy towards functionalized furo[3,2-c]pyranones.

A highly efficient multi-component anion relay cascade reaction based on 1-acetylcyclopropanecarboxamides, aldehydes and acrylonitrile has been developed, which provides strategically novel and atom-economic access to biologically important biscyanoethylated furo[3,2-c]pyridinones. In this one-pot transformation, up to five bonds (one C–N, one C–O and three C–C bonds) were constructed.

A simple, efficient and practical copper-catalyzed aerobic oxidative synthesis of α-ketoamides from aryl methyl ketones, aliphatic amines and N-iodosuccinimide (NIS) has been developed. The one-pot reaction may proceed smoothly at room temperature in the open air. The possible mechanism for the formation of α-ketoamides was proposed. Molecular oxygen in air functions as both an oxidant and an oxygen source.