3-Cyanomethylated imidazopyridines were synthesized via a visible light-promoted reaction of imidazopyridines with bromoacetonitrile or iodoacetonitrile catalyzed by fac-Ir(ppy)3 under mild conditions. For the substrates with various substituents on benzene or pyridine ring, the reaction proceeded smoothly to give the corresponding products in moderate to good yields. The synthetic utility of this visible-light-induced reaction has been illustrated in the efficient synthesis of zolpidem and alpidem.

A novel visible-light-induced cascade reaction for the preparation of ester-functionalized polyheterocycles was developed under metal-free conditions, which was initiated by an intermolecular radical addition to a carbon–carbon double bond of N-arylacrylamide derivatives using alkyl carbazate as the ester source followed by cyano-mediated cyclization. The desired phenanthridine derivative products were isolated in moderate to high yields with broad substrate scope.

A radical addition/nitrile insertion/homolytic aromatic substitution (HAS) cascade reaction to prepare 6-quaternary alkylated phenanthridines was developed. The addition of the active methylene radicals which were generated from 2-bromoacetonitrile, ethyl 2-bromoacetate, 2-bromo-N,N-dimethylacetamide, or 2-bromo-1-phenylethan-1-one to carbon–carbon double bonds of N-arylacrylamides followed by the cyano-participating sequential cyclization produced a series of phenanthridines in moderate to good yields under photoredox catalysis.

A visible light-induced regioselective sulfonamidation of imidazo[1,2-a]pyridines was developed using sulfamides as the nitrogen sources and aqueous NaClO solution as the oxidant under mild conditions. With the imidazo[1,2-a]pyridines bearing various substituents, the reaction proceeded smoothly to furnish the C3-sulfonamidation products in moderate to good yields. The method was also suitable for the sulfonamidation of some other imidazoheterocycles.

Heterocyclic derivatives 4-(nitromethyl)isoquinoline-1,3(2H,4H)-diones were synthesized via a tandem nitration/cyclization reaction of N-alkyl-N-methacryloyl benzamides under metal-free conditions. The cheap and available reagent nitrogen dioxide was used as the nitro source, as well as the oxidant. For the substrates with various substituent groups, the reaction proceeded smoothly to give the corresponding isoquinolinedione derivatives in moderate to good yields. The products could be converted into aminomethyl or hydroxyl substituted heterocyclic derivatives by the simple reduction.

The C3-azolylation of imidazo[1,2-a]pyridines was developed via a visible light-mediated reaction of imidazopyridines with 2-bromoazoles catalyzed by Ir(ppy)2(dtbbpy)PF6 under mild conditions. For the imidazo[1,2-a]pyridines with various substituents on benzene or the pyridine ring and a variety of azoles, the reaction proceeded smoothly to give 3-(azol-2-yl)imidazo[1,2-a]pyridines in moderate to good yields.

A facile H3PO4-promoted bridging methylenation of imidazopyridines or similar heterocycles has been described for the synthesis of symmetrical methylene-bridged imidazoheterocycles, in which DMSO was used as the carbon source. The reaction obtained good yields for most substrates with high C3-regioselectivity. This method also features metal-free, practicability and low cost.

A copper-catalyzed coupling reaction of sulfonyl chlorides with tertiary amines via the oxidative C–N bond cleavage of tertiary amines was developed. Sulfonamides were synthesized using this strategy in moderate to good yields. The reaction was applicable to various tertiary amines, as well as sulfonyl chlorides.

1,2-Diketones were synthesized by the oxidation of corresponding alkynes using air as the oxidant under metal-free conditions upon irradiation of blue light. A cheap and readily available organic dye, eosin Y, was used as the photocatalyst. For various substituents on the aryl ring, the reaction proceeded smoothly to give the dicarbonylation products in moderate to good yields. Some oxidation-sensitive groups, such as formyl and the carbon–carbon double bond, were tolerated under the developed reaction conditions.

Cyanomethylated coumarins were synthesized via cyanomethylation and cyclization of aryl alkynoates using cheap and available reagent acetonitrile as the cyanomethyl source in the presence of TBPB (tert-butyl peroxybenzoate) under transition-metal-free conditions. For the substrates with various substituents on benzene ring, the reaction proceeded smoothly to give the corresponding products in moderate to good yields. The resulting products could be simply converted into some other related coumarin derivatives.

A regioselective alkoxycarbonylation of imidazoheterocycles using carbazates as ester group sources in DMSO was developed, in which an inexpensive FeCl2·4H2O was used as the catalyst and (NH4)2S2O8 was the oxidant. The reaction proceeded smoothly under an air atmosphere to give the 3-alkoxycarbonylated products in moderate to good yields.

A tunable decarboxylative alkylation of cinnamic acids with alkanes was developed to form alkenes or ketones under transition metal-free conditions. In the presence of DTBP or DTBP/TBHP, the reaction gave alkenes and ketones respectively via a radical mechanism in moderate to good yields.

Aryl methyl thioethers and methylene-bridged arylamines were synthesized via highly regioselective para-methylthiolation/bridging methylenation of arylamines using DMSO as the methylthio or methylene source in the presence of NH4I under metal-free conditions. For the substrates with both electron-donating and electron-withdrawing substituents, the reaction proceeded smoothly and gave moderate to good yields.

2-(Alkylamino)benzonitriles were synthesized via a rhodium-catalyzed cyanation on the aryl C–H bond and subsequent denitrosation of N-nitrosoarylamines using a removable nitroso as the directing group, in which N-cyano-N-phenyl-p-methylbenzenesulfonamide (NCTS) was used as the “CN” source. Various substituents on the aryl ring and amino group of N-nitrosoarylamines tolerated the reaction, and the corresponding products were achieved in moderate to good yields.

A regioselective synthesis of 3-fluorinated imidazo[1,2-a]pyridines using 1-chloromethyl-4-fluoro-1,4-diazoniabi cyclo[2.2.2]octane bis(tetrafluoroborate) (Selectfluor) as the fluorinating reagent in aqueous condition is described. In the presence of DMAP, the reaction mainly gave monofluorinated product via electrophilic fluorinated process in moderate to good yields.

An efficient synthesis of phenols via Pd-catalyzed, pyridyl-directed homogeneous hydroxylation of the aryl C–H bond was developed, in which tert-butyl hydroperoxide was used as the sole oxidant. The method had a broad group tolerance and was available for both electron-rich and electron-deficient substrates. The reaction of a series of 2-arylpyridine derivatives gave the ortho-hydroxylation products in moderate to good yields.

A palladium-catalyzed direct sulfonylation of 2-aryloxypyridines on the ortho-position of the benzene ring was developed using 2-pyridyloxyl as the directing group and sulfonyl chlorides as sulfonylation reagents. The protocol was available for both electron-rich and electron-deficient substrates. The ortho-sulfonylated phenol was synthesized expediently from the sulfonylation product by the removal of the pyridyl group.

A palladium-catalyzed direct ortho-nitration reaction of azoarenes was developed in which NO2 was used as both nitro source and oxidant for the first time. The nitration products were converted into o-aminoazoarenes or benzotriazole derivatives by a simple reduction.

A new protocol for C–S and C–Se bond formation by the direct functionalization of the C(sp3)–H bond of alkanes under metal-free conditions was developed. Using tBuOOtBu as the oxidant, the reaction of disulfides or diselenides with alkanes gave sulfides or selenides in moderate to good yields. The method was very simple and atom-economical.

A novel two-dimensional metal–organic framework has been constructed from Fe3+ and meso-tetra(4-imidazoyl)porphyrin, which can remain in saturated (~27.5 M) NaOH solution for a week. To the best of our knowledge, this is the first report of a MOF that is stable in saturated NaOH solution. The utilization of an imidazolyl-based porphyrin ligand and a high-valence metal is a new and promising strategy for constructing porphyrinic MOFs with ultra-high stability.

The nBu4NI-catalyzed sequential C–O and C–N bond formation via multiple sp3C–H bond activation of ethylarenes, using N,N-dialkylformamide as the amino source, provided α-ketoamides with moderate yields.

Thiol and selenol esters were synthesized by a direct oxidative coupling reaction of aldehydes with disulfides or diselenides in ethyl acetate under metal-free conditions. Among the oxidants examined, tert-butyl peroxide (TBP) was shown to give the best results. For the substrates with both electron-donating and electron-withdrawing substituents, the reaction proceeded smoothly and gave moderate to good yields. Compared with the previous method, the present route is very simple, atom-economical and environmentally friendly.

A palladium-catalyzed direct ortho-alkoxylation of N-alkyl-N-nitrosoarylamines was developed in which alcohols were used as the alkoxylation reagents and PhI(OAc)2 was employed as the oxidant. The protocol was available for both primary and secondary alcohols. The products were transformed to o-alkoxy-N-alkylanilines expediently by a simple reduction.

An efficient and highly regioselective palladium-catalyzed ortho-C(sp2)–H bond alkoxylation of 2-aryloxypyridines was developed using 2-pyridyloxyl as the directing group and alcohols as alkoxylation reagents. Under an air atmosphere and in the presence of PhI(OAc)2, the reaction gave the corresponding products in moderate to good yields, and a series of functional groups could be tolerated.

This note describes the efficient and highly regioselective synthesis of 2-(2′-alkenylphenyl)phenol derivatives via palladium-catalyzed 2′-alkenylation of 2-arylphenols directed by the phenolic hydroxyl group using benzoquinone as the oxidant in an atmosphere of air. This reaction can tolerate a series of functional groups and provides the alkenylation products regio- and stereoselectively in moderate to good yields.

The oxidative coupling of methylarenes and N,N-dialkylformamides was developed, and the appropriate reaction conditions were established. By using I2 as the catalyst, and tert-butyl hydroperoxide (TBHP) as the oxidant, the reaction provided N,N-dialkylamides or N-alkylamides with moderate yields via multiple sp3 C-H bonds activation of methylarenes in aqueous and metal-free conditions.

A facile ortho-acylation of 2-arylpyridines by a Pd-catalyzed oxidative C–H activation was developed, in which no prefunctionalized toluene derivatives were used as acylation reagents in a tandem reaction to form 2-pyridyldiaryl ketones with moderate yields.

An efficient and highly regioselective synthesis of 2-alkoxy aromatic azo compounds via palladium(II)-catalyzed alkoxylation of azobenzene derivatives directed by the azo group using alcohols as the alkoxylation reagents and PhI(OAc)2 as the oxidant has been developed. The method is applicable to both primary and secondary alcohols and affords moderate to good yields.

A palladium-catalyzed ortho-halogenation (I, Br, Cl) of arylnitrile is described. The optimal reaction conditions were identified after examining various factors such as catalyst, additive, solvent, and reaction temperature. Using cyano as the directing group, the halogenation reaction gave good to excellent yields. The method is compatible to the arylnitriles with either electron-withdrawing or electron-donating groups. The reaction is available to the substrate in at least gram scale. The present method was successfully applied to the synthesis of the precursors of paucifloral F and isopaucifloral F.

Fe3O4 and Pd nanoparticles were assembled on sulfonated graphene (s-G) by an easy chemical approach and characterized by transmission electron microscopy, X-ray diffraction and energy dispersive X-ray spectroscopy. The resulting material could be dispersed homogeneously in water or water/ethanol and further used as an excellent semi-heterogeneous catalyst for the Suzuki–Miyaura cross-coupling reaction in an environmentally friendly solvent under ligand-free ambient conditions. The high heterogeneous catalytic activity appears to be due to the small size of Pd nanoparticles and homogeneous distribution of the nanoparticles on the Fe3O4/s-G matrix. In addition, the catalytic activity did not deteriorate even after repeated applications, which may be due to the easy and efficient magnetic separation of the catalyst and the high dispersion and stability of the catalyst in an aqueous solution.

A facile ortho-acylation of acetanilides by a Pd-catalyzed oxidative C–H activation was developed in which low toxic, stable, and commercially available toluene derivatives were first used as acylation reagents by a tandem reaction to form o-acylacetanilides with moderate to good yields. Inexpensive, safe, and environmentally benign TBHP was proved to be an effective oxidant for these transformations.

A Pd(OAc)2-catalyzed ortho-alkoxylation of arylnitrile was described. Using cyano as a directing group, the aromatic C–H bond can be functionalized efficiently to generate ortho-alkoxylated arylnitrile derivatives with moderate yields. The optimal reaction conditions were identified after examining various factors such as oxidant, solvent, and reaction temperature. The method was compatible to the arylnitriles with either electron-withdrawing or electron-donating groups.

PdII-catalyzed aromatic C−H bond activation using cyano as a directing group was carried out in TFA medium. Biphenyl-2-carbonitrile derivatives were therefore synthesized from aryl nitriles and aryl halides in moderate to good yields.

A Pd(OAc)2-catalyzed cross-coupling reaction between 2-arylpyridine and aryltrimethoxysilane in the presence of AgF and BQ in 1,4-dioxane was studied. After various reaction parameters (catalyst, oxidant, additive, solvent and reaction temperature) were examined, the optimal conditions for the reaction were identified. The synthesis is compatible to aryltrimethoxysilane with both electron-withdrawing and electron-donating groups on the aryl moiety with moderate yields. The kinetic isotope effect (kH/kD) for the C–H bond activation was provided.

A red-emitting iridium complex (DMBA)2Ir(acac) (DMBA = 5,6-dihydro-9,10-methylenedioxy benzo[c]acridine, acac = acetylacetone) containing rigid cyclometalated ligand DMBA was synthesized and its photophysical, electrochemical and electroluminescent properties were characterized. Organic light emitting devices utilizing the complex as dopant emitter were fabricated. When double hole-transporting layers were adopted, the brightness and efficiencies of electroluminescent devices were improved greatly. Based on the excimer emission, a maximum brightness of 66,312 cd m−2 at 15 V, together with a maximum external quantum efficiency of 17.7% at 5.0 V was achieved at a doping concentration of 5%. The result suggests that the introduction of a methylenedioxy group into the N-heterocycle of the cyclometalated ligand leads to higher-energy MLCT transitions and a blue shift of the photoluminescence spectrum.

By utilizing the relatively broad orange–red excimer emission of an iridium complex (DMBA)2Ir(acac) (DMBA = 5,6-dihydro-9,10-methylenedioxy-benzo[c]acridine, acac = acetylacetonate) together with an efficient blue phosphorescent iridium complex FIrpic, two types of efficient white organic light-emitting diodes were fabricated. Through the optimization of the thickness, location, and doping concentration of each emitting layer, both of the two types of devices exhibited pure white emission with CIE coordinates close to the ideal white emission (0.33, 0.33). Compared with the double-emitting-layer structure, a triple-emitting-layer device structure with a blue-emitting layer sandwiched between two orange–red-emitting layers led to more stable white emission at different biases/brightnesses with maximum efficiencies of up to 12.2%, and 27.0 cd A−1 for the forward viewing direction, corresponding to the total efficiencies of 19.7%, 45.9 cd A−1 and 32.1 lm W−1. At a high brightness of 1000 cd m−2, the EL efficiencies remained high at 8.8% and 19.2 cd A−1.

Three mononuclear Cu(I) complexes [Cu(bop)(PPh3)2][BF4], [Cu(fop)(PPh3)2][BF4] and [Cu (pop)(PPh3)2][BF4] were synthesized, where 2-(5-tert-butyl-1,3,4-oxadiazol-2-yl)pyridine (bop), 2-(5-(trifluoromethyl)-1,3,4-oxadiazol-2-yl)pyridine (fop) or 2-(5-phenyl-1,3,4-oxadiazol-2-yl)pyridine (pop) was used as N∧N chelate ligand and triphenylphosphine was used as ancillary ligand. Several substituents with different electronic effects, such as tert-butyl (t-Bu), trifluoromethyl (CF3) and phenyl (Ph) groups, were introduced into the 1,3,4-oxadiazole moiety of the N∧N chelate ligands. The photophysical properties of the complexes were examined by UV–vis absorption and photoluminescence (PL) spectroscopies. The complex [Cu(fop)(PPh3)2][BF4] with a CF3 group in the N∧N chelate ligand exhibited the lowest energy absorption and emission band. Electrochemical analyses combined with density functional theory (DFT) calculations established that the introduction of electron withdrawing group (CF3) decreases the HOMO–LUMO energy gap, and the introduction of electron donating group (t-Bu) into the 1,3,4-oxadiazole moiety has a similar effect on the emission wavelength as that of the introduction of a phenyl group with a π-conjugation.

In this paper, a luminescent complex of terbium–acetylsalicylic acid (Tb-ASA) was studied for the first time using combination of the quantum chemical calculation, fluorescence spectroscopic method and X-ray photoelectron spectroscopy (XPS). The results from the quantum chemical calculation indicated that it is possible for the energy-transfer from ASA to Tb (III); Fluorescence spectroscopy demonstrated that there is an intramolecular energy-transfer from ASA to Tb with the efficiency (III) of about 87.9% under an excitation at 308 nm. The XPS indicated that the coordinate covalent bond between Tb and O existed in the complex of Tb-ASA leads to the effective energy transfer from ASA to Tb (III) because the energy transfer rate may be improved with reducing the distance between the ligand and Tb (III). The results will have important values for the studies of this type of complexes.

Two phosphorescent iridium complexes (psbi)2Ir(acac) and (ppbi)2Ir(acac) (psbi = 1-phenyl-2-styryl-1H-benzo[d]imidazole, ppbi = 1-phenyl-2-(1-phenylprop-1-en-2-yl)-1H-benzo[d]imidazole, acac = acetylacetonate) were synthesized, and their photophysical, electrochemical and electroluminescent properties were also studied. Organic light-emitting devices with these two complexes as dopant emitters having the structure ITO/NPB (10 nm)/TCTA (20 nm)/x%Ir:CBP (y nm)/BCP (10 nm)/LiF (1 nm)/Al (100 nm) were fabricated. The device based on (psbi)2Ir(acac) exhibited a maximum brightness of 56,162 cd m−2, while the device based on (ppbi)2Ir(acac) gave a maximum brightness of 31,232 cd m−2. At high brightness of 1000 cd m−2 and 10,000 cd m−2, high current efficiencies of 25.7 cd A−1 and 20.7 cd A−1 were achieved, respectively, for the (psbi)2Ir(acac)-based EL device. For the EL device based on (ppbi)2Ir(acac), current efficiencies of 20.1 cd A−1 at 1000 cd m−2 and 14.2 cd A−1 at 10,000 cd m−2 were observed.

A phosphorescent iridium(III) complex Ir(PBQ)2(acac) (PBQ: 4-phenylbenzoquinoline, acac: acetylacetone) was designed and synthesized, and the single crystal of this complex was obtained. This complex shows well optoelectronic properties. The organic light emitting devices (OLEDs) based on this complex were successfully fabricated with the device configuration of ITO/NPB or TCTA (40 nm)/Ir-complex: CBP (7%, 30 nm)/BCP (15 nm)/Alq (30 nm)/LiF (1 nm)/Al (100 nm). Using TCTA as the hole-transporting material, the device gives an extremely high external quantum efficiency of 14.6% at 5.0 V, a brightness of 61,693 cd/m2 at 16.0 V, and a power efficiency of 37.0 lm/W at 3.5 V.

Two red emitting iridium complexes (DBA)2Ir(acac) and (BA)2Ir(acac) (DBA = 5,6-dihydro-benzo[c]acridine, BA = benzo[c]acridine, acac = acetylacetone) were synthesized. Organic light-emitting devices using these complexes as dopant emitters have been fabricated. The results showed that these complexes have strong phosphorescent characters and the devices emit pure red light. The maximum brightness of the device based on (DBA)2Ir(acac) is 9540 cd/m2 with an external quantum efficiency of 4.66%.

Heck reaction catalyzed by cobalt hollow nanospheres has been developed; the coupling of alkenes with aryl iodide or aryl bromide in the presence of potassium carbonate provides the corresponding products with moderate to good yields, which reveals obvious advantages such as low-cost catalyst, ligand-free condition, the recyclability of the catalyst and simple experimental operation.

PdCo bimetallic hollow nanospheres with a diameter of about 80 nm were for the first time synthesized in polyethylene glycol solution. This new Pd-containing bimetallic hollow nanostructure was successfully applied to catalysis of the Sonogashira reaction, which reveals obvious advantages such as environmentally friendly reaction conditions (the reaction proceeded in water), the recyclability of the catalyst, simple experimental operation and high yields.

Porous palladium nanoparticles were prepared using a solution-phase approach. Their structures and shapes were analyzed by XRD, EDS, TEM and HRTEM. These palladium nanoparticles were used to catalyze the cycloisomerization reaction of N,N-diallylamide or N,N-diallylsulfonamide, and N-acyl-2,3-dihydropyrrole or N-sulfonyl-2,3-dihydropyrrole derivatives were therefore synthesized with very high regioselectivity and in good yields. The nano-palladium catalyst showed high efficiency and it can be reused several times. A hydropalladation mechanism was proposed for this reaction.

Heterocyclic derivatives 4-(nitromethyl)isoquinoline-1,3(2H,4H)-diones were synthesized via a tandem nitration/cyclization reaction of N-alkyl-N-methacryloyl benzamides under metal-free conditions. The cheap and available reagent nitrogen dioxide was used as the nitro source, as well as the oxidant. For the substrates with various substituent groups, the reaction proceeded smoothly to give the corresponding isoquinolinedione derivatives in moderate to good yields. The products could be converted into aminomethyl or hydroxyl substituted heterocyclic derivatives by the simple reduction.

The C3-azolylation of imidazo[1,2-a]pyridines was developed via a visible light-mediated reaction of imidazopyridines with 2-bromoazoles catalyzed by Ir(ppy)2(dtbbpy)PF6 under mild conditions. For the imidazo[1,2-a]pyridines with various substituents on benzene or the pyridine ring and a variety of azoles, the reaction proceeded smoothly to give 3-(azol-2-yl)imidazo[1,2-a]pyridines in moderate to good yields.

Heterocyclic derivatives 4-(sulfonylmethyl)isoquinoline-1,3(2H,4H)-diones were synthesized via a visible-light-promoted reaction of N-alkyl-N-methacryloyl benzamides with sulfonyl chlorides catalyzed by fac-Ir(ppy)3 at room temperature. With various substituents on the substrates, the reaction proceeded smoothly to give the corresponding products in good to excellent yields. The products could be converted into 3-hydroxy-4-(sulfonylmethyl)-3,4-dihydroisoquinolin-1(2H)-one derivatives by the reduction of NaBH4.

This review summarizes advances in the decarboxylative alkylation of carboxylic acids and their derivatives under transition metal-free conditions in recent years. Unlike most transition metal-catalyzed decarboxylative coupling reactions which tend to undergo catalytic cycles, the mechanisms of reactions under metal-free conditions are usually diverse and even ambiguous in some cases. This article offers an overview of reaction types and their corresponding mechanisms, highlights some of the advantages and limitations, and focuses on introducing UV and visible light-induced, organocatalyst and peroxide promoted radical processes for decarboxylative alkylation and the formation of C–C bonds.

Correction for ‘Transition metal-free decarboxylative alkylation reactions’ by Ping Liu et al., Org. Biomol. Chem., 2016, DOI: 10.1039/c6ob02101h.

Fe3O4 and Pd nanoparticles were assembled on sulfonated graphene (s-G) by an easy chemical approach and characterized by transmission electron microscopy, X-ray diffraction and energy dispersive X-ray spectroscopy. The resulting material could be dispersed homogeneously in water or water/ethanol and further used as an excellent semi-heterogeneous catalyst for the Suzuki–Miyaura cross-coupling reaction in an environmentally friendly solvent under ligand-free ambient conditions. The high heterogeneous catalytic activity appears to be due to the small size of Pd nanoparticles and homogeneous distribution of the nanoparticles on the Fe3O4/s-G matrix. In addition, the catalytic activity did not deteriorate even after repeated applications, which may be due to the easy and efficient magnetic separation of the catalyst and the high dispersion and stability of the catalyst in an aqueous solution.

A tunable decarboxylative alkylation of cinnamic acids with alkanes was developed to form alkenes or ketones under transition metal-free conditions. In the presence of DTBP or DTBP/TBHP, the reaction gave alkenes and ketones respectively via a radical mechanism in moderate to good yields.

Heck reaction catalyzed by cobalt hollow nanospheres has been developed; the coupling of alkenes with aryl iodide or aryl bromide in the presence of potassium carbonate provides the corresponding products with moderate to good yields, which reveals obvious advantages such as low-cost catalyst, ligand-free condition, the recyclability of the catalyst and simple experimental operation.

The nBu4NI-catalyzed sequential C–O and C–N bond formation via multiple sp3C–H bond activation of ethylarenes, using N,N-dialkylformamide as the amino source, provided α-ketoamides with moderate yields.

A facile H3PO4-promoted bridging methylenation of imidazopyridines or similar heterocycles has been described for the synthesis of symmetrical methylene-bridged imidazoheterocycles, in which DMSO was used as the carbon source. The reaction obtained good yields for most substrates with high C3-regioselectivity. This method also features metal-free, practicability and low cost.

A copper-catalyzed coupling reaction of sulfonyl chlorides with tertiary amines via the oxidative C–N bond cleavage of tertiary amines was developed. Sulfonamides were synthesized using this strategy in moderate to good yields. The reaction was applicable to various tertiary amines, as well as sulfonyl chlorides.

Aryl methyl thioethers and methylene-bridged arylamines were synthesized via highly regioselective para-methylthiolation/bridging methylenation of arylamines using DMSO as the methylthio or methylene source in the presence of NH4I under metal-free conditions. For the substrates with both electron-donating and electron-withdrawing substituents, the reaction proceeded smoothly and gave moderate to good yields.

Thiol and selenol esters were synthesized by a direct oxidative coupling reaction of aldehydes with disulfides or diselenides in ethyl acetate under metal-free conditions. Among the oxidants examined, tert-butyl peroxide (TBP) was shown to give the best results. For the substrates with both electron-donating and electron-withdrawing substituents, the reaction proceeded smoothly and gave moderate to good yields. Compared with the previous method, the present route is very simple, atom-economical and environmentally friendly.