Sulfonated oxindoles are accessed by a Cu(OAc)2-catalyzed three-component reaction of N-(arylsulfonyl)acrylamides, DABSO, and aryldiazonium tetrafluoroborates. This transformation is triggered by the formation of arylsulfonyl radicals in situ from the reaction of aryldiazonium tetrafluoroborates and DABSO. Afterward, the sequential radical addition, radical cyclization, and desulfonylative 1,4-aryl migration take place to provide the final product by the formation of four new bonds in one pot. This procedure shows good functional group tolerance.

A palladium-catalyzed cyanation of aryl halides with hexamethylenetetramine as a safe cyanide source is achieved, providing aromatic nitriles in moderate to good yields. This approach shows good functional group compatibilities and avoids the use of toxic cyanide source.

In the presence of tert-butyl peroxide (TBHP), the copper-catalyzed annulation of 1,3-dicarbonyl compound with diethylene glycol was developed leading to 2,3-disubstituted furan. Diethylene glycol serves as a cheap and environmentally friendly equivalent of ethyne, with the release of H2O and alcohol as clean wastes. The procedure involves a sequential O- and C- functionalization of β-ketoester by diethylene glycol.

A cyanide-free one-pot procedure was developed to access 2-amino-3-hydroxy-3H-indoles, which involved: (1) in situ formation of ketenimines by the reaction of N′-(1-(2-aminophenyl)ethylidene)-p-tosylhydrazones with isonitriles; (2) the intramolecular nucleophilic attack of ketenimines by the amino in phenyl furnishing the ring closure leading to 2-aminoindoles; (3) the oxidation of 2-aminoindoles by O2 leading to 2-amino-3-hydroxy-3H-indoles. This strategy represents not only a key compliment to the sporadic synthetic methods toward 2-amino-3-hydroxy-3H-indoles but also progress in N-tosylhydrazone, isonitrile, and ketenimine chemistry.

A palladium-catalyzed annulation of ortho-vinylanilines with dimethyl sulfoxide was developed to access 4-aryl quinolines in moderate to good yields. Activated by 1,4-diazabicyclo[2.2.2]octane bis(sulfur dioxide) adduct (DABSO), DMSO served as a “CH–” fragment in this transformation. It represents a facile pathway leading to 4-aryl quinolines.

A copper-mediated annulation of 2-(1-substituted vinyl) anilines and aryl nitrosos is developed for the synthesis of 2,3-diaryl pyrazoles. Compared with previously reported sequential azobenzene C–H ortho-acylation, reduction and cyclization procedures towards such frameworks, no external reductant was required during this cyclization, where the vinyl served as a formal innate reductant. Moreover, in this procedure, no selectivity was involved in the case of Ar1 ≠ Ar2.

•3-Aminopropanol served as both a four-atom subunit and solvent in this reaction.•Imine formation, alcohol oxidation and cyclization may involve in this reaction.•This strategy features with good yields and good functional group compatibility.An iridium-catalyzed annulation between 1,2-diarylethanone and 3-aminopropanol was developed, leading to site specific 2,3-diarylpyridines in moderate yields. 3-Aminopropanol served as both a four-atom component and solvent during this procedure, releasing water as a clean by-product. The reaction may proceed with sequential imine formation, alcohol oxidation and intramolecular cyclization by Knoevenagel reaction.Download high-res image (64KB)Download full-size image

AbstractA palladium-catalyzed [5+1] annulation of 2-(1-arylvinyl) anilines and α-diazocarbonyl compounds has been developed, affording a series of multi-functionalized quinolines in moderate to good yields. This procedure proceeded with the sequential insertion of N−H bond to the palladium carbene, intramolecular Heck reaction and decarboxylation steps. In this reaction, alkyl 2-diazophenylacetates served as C1 building block, which represents a key compliment to diazo chemistry.

AbstractThe straightforward functionalization of simple alkanes (simple alkanes refer particularly to cyclohexane derivatives) has been a challenging subject in modern chemistry. However, with the development of oxidative radical reaction, it provided an available and alternative approach to meet the requirement of activating these compounds. In the review, we summarized the recent advances in this field, and the review mainly contained the following four parts: (1) the formation of C—C bonds; (2) the formation of C—N bonds; (3) the formation of C—S bonds and (4) the formation of C—O bonds.

A Rh(III)-catalyzed bilateral cyclization was developed for the efficient construction of acridines proceeding with C–H functionalization whereby in situ formation and removal of an imino transient directing group in the presence of catalytic amount of BnNH2 are achieved. In this transformation, a sequential Rh(III)-catalyzed C–H amination, cyclization, and aromatization process was involved.

A palladium-catalyzed, three-component reaction between propargylic alcohols, CO2, and aryl halides was developed whereby a sequential carboxylation, trans-oxopalladation of the C≡C bond by an ArPdX species, and a reductive elimination procedure afforded a series of functionalized α-alkylidene cyclic carbonates in moderate to excellent yields. Notably, the configuration of these tetrasubstituted olefins was dominated by the trans-oxopalladation step where the aryl group derived from ArX is located trans to the oxygen attached in the double bond. This protocol features simultaneous formation of four novel bonds in a one-pot reaction, representing an efficient method for incorporation of CO2 into heterocycles.

A three-component reaction of quaternary ammonium salts, N-substituted formamides and aqueous sodium disulfide was developed, leading to aryl/heteroaryl thioamides in moderate to good yields with good functional group compatibility. This procedure was featured with the combination of three reaction partners, rendering an important complementary to the previously reported methods for the synthesis of aryl thioamides, and was beneficial to the chemistry of functional group transformations. No external oxidant was required in this procedure.

AbstractA base-promoted annulation of 2-hydrazinyl pyridine and atmospheric pressure of CO2 has been developed in the presence of silane as reducing reagent, affording a series of triazolones in moderate to excellent yields. CO2 served as a carbonyl source in this transfomation. Moreover, benzamidrazones also worked well under this procedure. Thus, it represents a green, sustainable and straightforward pathway to access triazolone frameworks.

•In this procedure, the starting materials are easy to be prepared.•This strategy leads to a series of unsymmetric 2,4,6-triaryl pyrimidines.•DMSO was activated by base rather than either Lewis acid or electrophile.A base-promoted formal [4 + 1+1] annulation of aldehyde, N-benzyl amidine and DMSO was developed, leading to a series of 2,4,6-triaryl pyrimidines in moderate to good yields. Notably, DMSO served as a methine source, which was activated by base rather than either Lewis acid or electrophile. Molecular O2 was the sole eco-friendly oxidant during this procedure.Download high-res image (55KB)Download full-size image

•High chemical diversity and complexity of the products by multicomponent reaction.•The employment of elemental sulfur and commercially available starting material under transition metal-free conditions.•Wide substrates scope.A base-promoted three-component reaction between arylmethyl bromides, arylamidines and elemental sulfur was developed, leading to unsymmetric 3,5-diaryl-1,2,4-thiadiazoles in moderate to good yields with chemical diversity and complexity. This procedure shows broad substrates scope by employing elemental sulfur and commercially available starting materials under transition-metal free conditions.Download high-res image (62KB)Download full-size image

•DMSO served as a “CH” fragment during this procedure.•Activated by 1,4-diazabicyclo[2.2.2]octane bis(sulfur dioxide) adduct (DABSO)•Good yields, good functional group compatibility.A palladium-catalyzed annulation of 2-(aryldiazenyl) aniline and dimethyl sulfoxide was developed to access N-aryl-1H-benzo[d]imidazol-1-amine in moderate to good yields. Activated by 1,4-diazabicyclo[2.2.2]octane bis(sulfur dioxide) adduct (DABSO), DMSO served as a “CH” fragment during this procedure. It represents a facile pathway leading to benzimidazoles.Download high-res image (38KB)Download full-size image

A metal-free decarbonylative arylalkylation of N-(arylsulfonyl)acrylamides using aliphatic aldehydes as the alkyl radical source was developed, providing a series of α-aryl-β-alkylamides in moderate to good yields. In this reaction, concomitant alkylation, aryl migration and desulfonylation were involved.

A copper-catalyzed cascade radical 1,2-cyclization of indoles with arylsulfonyl hydrazides was developed, affording a series of 2-thiolated 3H-pyrrolo[1,2-a]indoles in moderate to excellent yields. This transformation proceeded with sequential radical addition to a triple bond and a cyclization procedure, where arylsulfonyl hydrazides served as thioarylation reagents.

A base-promoted dearomative annulation between N-2-pyridylamidine and an atmospheric pressure of CO2 was developed, affording a series of pyrido[1,2-a]-1,3,5-triazin-4-ones in moderate to excellent yields. CO2 served as a carbonyl source, releasing H2O as a solely clean byproduct. Moreover, no dehydrating reagent and transition-metal catalyst were required in this procedure. Thus, it represents a green, sustainable and straightforward pathway to access such frameworks.

A copper-mediated, three-component reaction between two different N-Ts hydrazones and elemental sulfur was developed, leading to a series of unsymmetric 2,5-disubstituted 1,3,4-thiadiazoles in moderate yields with good functional group compatibility. This procedure features the employment of elemental sulfur and the selective denitrogenation between aryl and alkyl aldehyde N-tosyl hydrazones, allowing rapid access to unsymmetric 2,5-disubstituted 1,3,4-thiadiazoles frameworks with chemical diversity and complexity.

•Neither catalyst nor oxidant was required in this procedure.•This strategy features high efficiency with operational simplicity.•Silver was not required in this transformation at all.An efficient protocol for the synthesis of thiophosphinates is presented, involving direct coupling of P–S bond between disulfides and H-phosphine oxide in moderate to good yields with good functional group compatibility. This procedure shows some advantages: (1) catalyst- and oxidant-free; (2) high efficiency with operational simplicity.

An unprecedented TBHP-promoted formal [3 + 2] annulation of sec-alcohols with α,α-diaryl allylic alcohols has been developed, leading to 2,3-dihydrofurans in moderate to excellent yields with good functional group tolerance. This procedure involves sequential radical addition, 1,2-aryl migration, and a dehydration process, where the migration of aryl with lower electron density is favored. Notably, cyclic reactions with sec-alcohols also ran smoothly, providing a novel method to access oxaspiro compounds.

Rhodium-catalyzed annulation of commercially available primary benzylamine with α-diazo ketone was developed, leading to isoquinolines in moderate to good yields. This procedure features the employment of primary benzylamine as starting material as well as high selectivity in the 3- and 4- position of isoquinoline, generating a key compliment to the previously developed annulation with internal alkyne.

An iron-mediated direct annulation between methylene ketones and diethanolamines was developed for the efficient synthesis of N-(2-hydroxyethyl) pyrroles. This protocol shows high efficiency, operational simplicity, good functional group compatibility as well as broad substrates scope.

A TBAI-catalyzed reaction between N-tosyl hydrazone and sulfur was developed, leading to 1,2,3-thiadiazoles in moderate to good yields. It represents a facile and practical procedure to access thiadiazole under metal-free conditions. This procedure serves as an improvement for the Hurd–Mori reaction.

An iron-catalyzed intermolecular [4 + 2] cyclization of arylnitrones with geminal-substituted vinyl acetates was developed for the synthesis of 2,4-disubstituted quinolines in moderate to good yields with good functional group compatibilities. Preliminary mechanistic studies suggest a plausible iron-catalyzed C–H activation process under external-oxidant-free conditions.

The development of organic transformation using cheap and readily available substrates under mild conditions will be pivotal for green and sustainable synthetic organic chemistry. Concerning our continued interest in the cyanation reaction, a metal-free direct ammoxidation of readily available methyl arenes leading to nitriles was established under mild conditions. A series of aryl methanes especially heteroaryl methanes (30 examples) were applicable in moderate to good yields with good functionality tolerance.

A palladium-catalyzed three-component reaction between N-tosyl hydrazones, aryl isonitriles and amines was developed, leading to amidines in moderate to good yields. This procedure features the rapid construction of amidine frameworks with high diversity and complexity. Ketenimines serve as intermediates, which encounter nucleophilic attack by amines to produce amidines.

A copper-catalyzed oxidative C(sp3)–H/N–H coupling of sulfoximines with simple alkanes was developed. This protocol involved C(sp3)–N bond formation via a radical pathway and tolerated a series of functional groups, such as chloro, methyl and aryl, on the phenyl rings. Apart from sulfoximines, amides, saccharin and aniline also worked well to give the corresponding N-alkylated products.

Palladium-catalyzed multi-component reactions (MCRs) between 2-iodoaniline, aryl isonitrile, N-tosylhydrazones and solvent were developed. This procedure features the migration of the imino group in palladium-carbene to produce a 3-aza π-allyl palladium species. Then, intramolecular nucleophilic attack of the π-allyl palladium species by the amino group takes place facilely, thus producing a 1,2,3-trisubstitued indole skeleton, which has high diversity and complexity.

The concise synthesis of 3-substituted or non-C3-substituted isoquinolines through Rh-catalyzed sequential oxidative C–H activation/annulation with geminal-substituted vinyl acetates was developed with good functional group tolerance. The protocol was successfully applied to the total synthesis of the natural product papaverine.

An unprecedented approach to N-trifluoromethylations of electron-rich nucleophilic sites following a radical pathway is reported. Accordingly, various sulfoximines (19 examples) have been N-trifluoromethylated, providing previously unreported products with satisfying functionality tolerance in moderate to good yields. With a C–N bond length at the N–CF3 moiety of 1.341 Å the respective linkage is shorter than a traditional C–N single bond and comparable with that of a C–N double bond.

The copper-catalyzed N-silylation of sulfoximines was achieved in the presence of di-tert-butyl peroxide. Notably, alkyl, phenyl and alkoxyl silanes were all suitable reaction partners. Mechanistic studies revealed that N-silyl acetamide serves as the intermediate.

A copper-catalyzed radical 1,2-aryl migration in α,α-diaryl allylic alcohols is developed, leading to β-silyl carbonyl compounds in moderate to good yields. The migration of aryls with lower aromaticity is favored. This procedure features the employment of silanes as commercially available materials.

A rhodium-catalyzed annulation between 2-arylimidazo[1,2-a]pyridines and alkynes was developed, leading to pyrido[1,2-a]benzimidazole derivatives in moderate to excellent yields. Notably, the ring C in pyrido[1,2-a]benzimidazole and the naphthalene framework were constructed consecutively, which provided a potential pathway leading to such a structure. This procedure tolerated chloro, bromo, cyano and methoxycarbonyl groups.

The direct copper-catalyzed N-cyanation of sulfoximines was achieved by using AIBN as a safe cyanide source. It represents a simple and environmentally benign procedure for the construction of the N–CN bond. Furthermore, some sec-amines can also be tolerated well under this procedure.

A Cs2CO3-promoted carboxylation of N-tosylhydrazones and CO2 has been developed. The reaction proceeded efficiently at 80 °C under atmospheric CO2, gave the corresponding α-arylacrylic acids in moderate to good yields. This method was featured with (1) the employment of Cs2CO3 rather than nBuLi as the base; (2) a reaction temperature of 80 °C rather than −78 °C.

The benzoyl peroxide-promoted α-phenanthridinylation of ether by isocyanide is developed, proceeding through dual C–H bond cleavage and dual C–C bond formation. The procedure tolerates a series of functional groups, such as methyl, fluoro, chloro, acetyl, methoxy carbonyl, cyano, and trifluoromethyl. Thus, it represents a facile pathway leading to 6-substituted phenanthridine derivatives. The addition of radical to the isonitrile followed by a radical aromatic cyclization is involved in this transformation.

An FeCl2-promoted carbomethylation of arylacrylamides by di-tert-butyl peroxide (DTBP) is achieved, leading to 3-ethyl-3-substituted indolin-2-one in high yield. The reaction tolerates a series of functional groups, such as cyano, nitro, ethyloxy carbonyl, bromo, chloro, and trifluoromethyl groups. The radical methylation and arylation of the alkenyl group are involved in this reaction.

The Bu4NI-catalyzed reaction of ketones with benzylic alcohols was achieved, leading to alfa-acyloxycarbonyl compounds in moderate to good yields. This metal-free procedure featured the employment of facilely and commercially available starting materials and TBHP as a clean oxidant with high atom economy.

The benzoyl peroxide (BPO)-promoted phenanthridinylation of simple alkanes with isonitrile is developed via C(sp3)–H and C(sp2)–H bond cleavage. This procedure is featured by dual C–C bond formation proceeding with the addition of an alkyl radical to isonitrile followed by radical aromatic cyclization.

The copper-catalyzed cyanation of disulfides by azobisisobutyronitrile (AIBN) was developed, leading to thiocyanates in moderate to good yields. This procedure tolerates a series of functional groups, such as chloro, nitro, methyl and methoxycarbonyl in the phenyl ring of disulfides. Notably, it enables the use of two ArS units in (ArS)2. CuI was found to be essential for the in situ formation of cyanide anions.

A copper-promoted C3-cyanation of both the free N–H and N-protected indoles by N,N,N′,N′-tetramethyl-ethane-1,2-diamine (TMEDA) and ammonium is achieved. The iminium ion acts as the intermediate in this transformation, which is sequentially electrophilically attacked by indole and H2O followed by hydrolyzation to form the aldehyde. Then the reaction between the aldehyde and ammonium afforded nitriles. The reaction employs O2 as a clean oxidant with good efficiency and functional group tolerance. Thus, it represents a facile and safe procedure leading to 3-cyano indoles.

A di-tert butyl peroxide (DTBP)-promoted α-alkylation of α-amino carbonyl compounds by simple alkanes is developed, proceeding through dual sp3 C–H bonds cleavage. The reaction was applicable for α-amino ketones and α-amino esters, providing a facile pathway for the α-functionalization of these substrates. The radical pathway is involved in this transformation.

The Rh-catalyzed direct annulation of an aldehyde with an alkyne leading to indenone was achieved. The in situ temporal installation of acetylhydrazine enables the annulation of the ortho arene C–H bond with alkynes to form ketone hydrazone. Subsequently, the in situ directing group removal takes place since ketone hydrazone is more susceptible toward hydrolysis than aldehyde hydrazone. Notably, this procedure tolerates a series of functional groups, such as methoxyl, acetylamino, fluoro, trifluoromethyl, methoxycarbonyl, chloro, and bromo groups.

DMSO and H2O is an efficient combination in the NH4OAc-promoted formylation of indole, where DMSO serves as a C1 carbon source. The mechanism study reveals that the procedure involves a usual and unusual Pummerer reaction.

A palladium-catalyzed arylation of benzoxazole has been developed. This protocol involves the tandem decarboxylation and oxidation of a carbon–carbon triple bond followed by decarbonylative arylation of the benzoxazole C–H bond.

A palladium-catalyzed cyanation of aryl halides and borons has been developed by employing cuprous thiocyanate as a safe cyanide source. This protocol avoids the use of a highly toxic cyanide source, providing aromatic nitriles in moderate to good yields with good functional tolerance.

A base-promoted formal arylation of benzo[d]oxazoles with acyl chloride was achieved in moderate to good yields. This reaction was triggered by the N-acylation of oxazole to form an iminium intermediate. Then, the addition of H2O to the iminium formed the hemiacetal intermediate. After the sequential ring-opening, extrusion of CO, the ring closure, the dehydration delivered the formal arylation product. In comparison with the transition-metal-catalyzed methodology, it represents an alternative arylation method leading to 2-arylbenzooxazole.

A Pd (OAc)2-catalyzed direct arylation of benzoxazole C–H bonds has been achieved with iodobenzene diacetates as the arylation reagent in moderate to good yields. The procedure tolerates a series of functional groups, such as methoxy, nitro, cyano, chloro, and bromo groups.

A copper-mediated annulation of 2-(1-substituted vinyl) anilines and aryl nitrosos is developed for the synthesis of 2,3-diaryl pyrazoles. Compared with previously reported sequential azobenzene C–H ortho-acylation, reduction and cyclization procedures towards such frameworks, no external reductant was required during this cyclization, where the vinyl served as a formal innate reductant. Moreover, in this procedure, no selectivity was involved in the case of Ar1 ≠ Ar2.

A metal-free decarbonylative arylalkylation of N-(arylsulfonyl)acrylamides using aliphatic aldehydes as the alkyl radical source was developed, providing a series of α-aryl-β-alkylamides in moderate to good yields. In this reaction, concomitant alkylation, aryl migration and desulfonylation were involved.

The benzoyl peroxide (BPO)-promoted phenanthridinylation of simple alkanes with isonitrile is developed via C(sp3)–H and C(sp2)–H bond cleavage. This procedure is featured by dual C–C bond formation proceeding with the addition of an alkyl radical to isonitrile followed by radical aromatic cyclization.

A copper-catalyzed oxidative C(sp3)–H/N–H coupling of sulfoximines with simple alkanes was developed. This protocol involved C(sp3)–N bond formation via a radical pathway and tolerated a series of functional groups, such as chloro, methyl and aryl, on the phenyl rings. Apart from sulfoximines, amides, saccharin and aniline also worked well to give the corresponding N-alkylated products.

A copper-promoted C3-cyanation of both the free N–H and N-protected indoles by N,N,N′,N′-tetramethyl-ethane-1,2-diamine (TMEDA) and ammonium is achieved. The iminium ion acts as the intermediate in this transformation, which is sequentially electrophilically attacked by indole and H2O followed by hydrolyzation to form the aldehyde. Then the reaction between the aldehyde and ammonium afforded nitriles. The reaction employs O2 as a clean oxidant with good efficiency and functional group tolerance. Thus, it represents a facile and safe procedure leading to 3-cyano indoles.

A Rh(III)-catalyzed bilateral cyclization was developed for the efficient construction of acridines proceeding with C–H functionalization whereby in situ formation and removal of an imino transient directing group in the presence of catalytic amount of BnNH2 are achieved. In this transformation, a sequential Rh(III)-catalyzed C–H amination, cyclization, and aromatization process was involved.

A palladium-catalyzed three-component reaction between N-tosyl hydrazones, aryl isonitriles and amines was developed, leading to amidines in moderate to good yields. This procedure features the rapid construction of amidine frameworks with high diversity and complexity. Ketenimines serve as intermediates, which encounter nucleophilic attack by amines to produce amidines.

A base-promoted dearomative annulation between N-2-pyridylamidine and an atmospheric pressure of CO2 was developed, affording a series of pyrido[1,2-a]-1,3,5-triazin-4-ones in moderate to excellent yields. CO2 served as a carbonyl source, releasing H2O as a solely clean byproduct. Moreover, no dehydrating reagent and transition-metal catalyst were required in this procedure. Thus, it represents a green, sustainable and straightforward pathway to access such frameworks.

A palladium-catalyzed annulation of ortho-vinylanilines with dimethyl sulfoxide was developed to access 4-aryl quinolines in moderate to good yields. Activated by 1,4-diazabicyclo[2.2.2]octane bis(sulfur dioxide) adduct (DABSO), DMSO served as a “CH–” fragment in this transformation. It represents a facile pathway leading to 4-aryl quinolines.

The copper-catalyzed N-silylation of sulfoximines was achieved in the presence of di-tert-butyl peroxide. Notably, alkyl, phenyl and alkoxyl silanes were all suitable reaction partners. Mechanistic studies revealed that N-silyl acetamide serves as the intermediate.

Palladium-catalyzed multi-component reactions (MCRs) between 2-iodoaniline, aryl isonitrile, N-tosylhydrazones and solvent were developed. This procedure features the migration of the imino group in palladium-carbene to produce a 3-aza π-allyl palladium species. Then, intramolecular nucleophilic attack of the π-allyl palladium species by the amino group takes place facilely, thus producing a 1,2,3-trisubstitued indole skeleton, which has high diversity and complexity.

The development of organic transformation using cheap and readily available substrates under mild conditions will be pivotal for green and sustainable synthetic organic chemistry. Concerning our continued interest in the cyanation reaction, a metal-free direct ammoxidation of readily available methyl arenes leading to nitriles was established under mild conditions. A series of aryl methanes especially heteroaryl methanes (30 examples) were applicable in moderate to good yields with good functionality tolerance.

A copper-catalyzed radical 1,2-aryl migration in α,α-diaryl allylic alcohols is developed, leading to β-silyl carbonyl compounds in moderate to good yields. The migration of aryls with lower aromaticity is favored. This procedure features the employment of silanes as commercially available materials.

DMSO and H2O is an efficient combination in the NH4OAc-promoted formylation of indole, where DMSO serves as a C1 carbon source. The mechanism study reveals that the procedure involves a usual and unusual Pummerer reaction.

An FeCl2-promoted carbomethylation of arylacrylamides by di-tert-butyl peroxide (DTBP) is achieved, leading to 3-ethyl-3-substituted indolin-2-one in high yield. The reaction tolerates a series of functional groups, such as cyano, nitro, ethyloxy carbonyl, bromo, chloro, and trifluoromethyl groups. The radical methylation and arylation of the alkenyl group are involved in this reaction.

The copper-catalyzed cyanation of disulfides by azobisisobutyronitrile (AIBN) was developed, leading to thiocyanates in moderate to good yields. This procedure tolerates a series of functional groups, such as chloro, nitro, methyl and methoxycarbonyl in the phenyl ring of disulfides. Notably, it enables the use of two ArS units in (ArS)2. CuI was found to be essential for the in situ formation of cyanide anions.

A rhodium-catalyzed annulation between 2-arylimidazo[1,2-a]pyridines and alkynes was developed, leading to pyrido[1,2-a]benzimidazole derivatives in moderate to excellent yields. Notably, the ring C in pyrido[1,2-a]benzimidazole and the naphthalene framework were constructed consecutively, which provided a potential pathway leading to such a structure. This procedure tolerated chloro, bromo, cyano and methoxycarbonyl groups.

The Bu4NI-catalyzed reaction of ketones with benzylic alcohols was achieved, leading to alfa-acyloxycarbonyl compounds in moderate to good yields. This metal-free procedure featured the employment of facilely and commercially available starting materials and TBHP as a clean oxidant with high atom economy.

The concise synthesis of 3-substituted or non-C3-substituted isoquinolines through Rh-catalyzed sequential oxidative C–H activation/annulation with geminal-substituted vinyl acetates was developed with good functional group tolerance. The protocol was successfully applied to the total synthesis of the natural product papaverine.