A new FeCl₃ and BF₃⋅OEt₂ co-catalyzed tandem hetero-[5+2] cycloaddition of 2-(2-aminoethyl)oxiranes with a wide range of alkynes, including terminal alkynes and alkyl-substituted internal alkynes is presented. This is the first example of rapid and facile production of diverse 2,3-dihydro-1H-azepines through a sequence of epoxide ring-opening, annulation, and dehydroxylation with broad substrate scope and exquisite selectivity control.

A new iron-facilitated silver-mediated radical 1,2-alkylarylation of styrenes with α-carbonyl alkyl bromides and indoles is described, and two new C−C bonds were generated in a single step through a sequence of intermolecular C(sp³)−Br functionalization and C(sp²)−H functionalization across the alkenes. This method provides an efficient access to alkylated indoles with broad substrate scope and excellent selectivity.

A new FeCl₃ and BF₃⋅OEt₂ co-catalyzed tandem hetero-[5+2] cycloaddition of 2-(2-aminoethyl)oxiranes with a wide range of alkynes, including terminal alkynes and alkyl-substituted internal alkynes is presented. This is the first example of rapid and facile production of diverse 2,3-dihydro-1H-azepines through a sequence of epoxide ring-opening, annulation, and dehydroxylation with broad substrate scope and exquisite selectivity control.

A new iron-facilitated silver-mediated radical 1,2-alkylarylation of styrenes with α-carbonyl alkyl bromides and indoles is described, and two new C−C bonds were generated in a single step through a sequence of intermolecular C(sp³)−Br functionalization and C(sp²)−H functionalization across the alkenes. This method provides an efficient access to alkylated indoles with broad substrate scope and excellent selectivity.

A new, metal-free method for the formation of C(sp³)–O bonds was established by PhI(OAc)₂-mediated oxygenation of benzylic C(sp³)–H bonds with N-hydroxyamides at room temperature, in which the C(sp³)–H oxidation is activated by a polyflurophenylamide group.

A new metal-free oxidative radical [2+2+1] carbocyclization of benzene-linked 1,n-enynes with two C(sp³)H bonds adjacent to the same heteroatom is described. This method achieves two C(sp³)H oxidative functionalizations and an annulation, thus providing efficient and general access to a variety of fused five-membered carbocyclic hydrocarbons.

A rhodium(III)-catalyzed [3+2]/[5+2] annulation of 4-aryl 1-tosyl-1,2,3-triazoles with internal alkynes is presented. This transformation provides straightforward access to indeno[1,7-cd]azepine architectures through a sequence involving the formation of a rhodium(III) azavinyl carbene, dual C(sp²)H functionalization, and [3+2]/[5+2] annulation.

A new metal-free radical 5-exo-dig cyclization of phenol-linked 1,6-enynes with O₂, 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO), and tBuONO is described. With this general method, carbonylated benzofurans can be accessed through incorporation of two oxygen atoms into the product from O₂ and TEMPO through dioxygen activation and oxidative cleavage of the NO bond, respectively.

A new metal-free oxidative radical [2+2+1] carbocyclization of benzene-linked 1,n-enynes with two C(sp³)H bonds adjacent to the same heteroatom is described. This method achieves two C(sp³)H oxidative functionalizations and an annulation, thus providing efficient and general access to a variety of fused five-membered carbocyclic hydrocarbons.

A rhodium(III)-catalyzed [3+2]/[5+2] annulation of 4-aryl 1-tosyl-1,2,3-triazoles with internal alkynes is presented. This transformation provides straightforward access to indeno[1,7-cd]azepine architectures through a sequence involving the formation of a rhodium(III) azavinyl carbene, dual C(sp²)H functionalization, and [3+2]/[5+2] annulation.

A new metal-free radical 5-exo-dig cyclization of phenol-linked 1,6-enynes with O₂, 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO), and tBuONO is described. With this general method, carbonylated benzofurans can be accessed through incorporation of two oxygen atoms into the product from O₂ and TEMPO through dioxygen activation and oxidative cleavage of the NO bond, respectively.

Alkynes serve as prevalent intermediates in the synthesis of natural products and pharmaceuticals. We here described a new and efficient route to internal alkynes by Pd-catalyzed Kumada cross-coupling reactions of alkynyl halides with Grignard reagents. In the presence of Pd(PPh₃)₄ and N¹,N¹,N²,N²-tetramethylethane-1,2-diamine (TMEDA), a variety of alkynyl halides underwent Kumada coupling with Grignard reagents, giving the corresponding internal alkynes in moderate to good yields.

Oxindoles are important heterocyclic compounds that are found in a wide range of pharmaceutical agents and natural products. A new oxidative tandem route to the assembly of 3-(2-oxoethyl)indolin-2-ones from N-arylacrylamides and alcohols has been established by using inexpensive and environmentally benign iron catalysts and peroxides. In the presence of Fe(OAc)₂ and tert-butyl hydroperoxide, a variety of arylacrylamides underwent the oxidative 1,2-carboacylation reaction with alcohols to give the corresponding 3-(2-oxoethyl)indolin-2-ones in moderate to good yields.

A general and conceptually novel method for preparing polychloro-substituted pyrrolidin-2-ones and indeno[2,1-c]pyrrol-3(3aH)-ones is established by visible-light-facilitated 5-exo-trig cyclization of 1,6-dienes with alkyl chlorides through selectively splitting the C(sp³)–H bond adjacent to the chloride atom to form an alkyl radical.

A new, mild route to access 3-methyleneindolin-2-ones is presented that proceeds through a room-temperature, palladium-catalyzed intramolecular oxidative aminocarbonylation of alkenes with amines and CO. This method represents a new aminocarbonylation strategy by employing an oxidative functionalization of a vinyl C(sp²)–H bond.

This study describes a new rhodium(III)-catalyzed [3+2] annulation of 5-aryl-2,3-dihydro-1H-pyrroles with internal alkynes using a Cu(OAc)₂ oxidant for building a spirocyclic ring system, which includes the functionalization of an aryl C(sp²)H bond and addition/protonolysis of an alkene CC bond. This method is applicable to a wide range of 5-aryl-2,3-dihydro-1H-pyrroles and internal alkynes, and results in the assembly of the spiro[indene-1,2′-pyrrolidine] architectures in good yields with excellent regioselectivities.

The oxidative interception of various σ-alkyl palladium(II) intermediates with additional reagents for the difunctionalization of alkenes is an important research area. A new palladium-catalyzed oxidative difunctionalization reaction of alkenes with α-carbonyl alkyl bromides is described, in which the σ-alkyl palladium(II) intermediate is generated through a Heck insertion and trapped using an aryl C(sp²)H bond. This method can be applied to various α-carbonyl alkyl bromides, including primary, secondary, and tertiary α-bromoalkyl esters, ketones, and amides.

A practical method for the synthesis of azepine derivatives, a typical seven-membered heterocyclic ring system, was developed and involves the use of hexafluoroantimonic acid to catalyze a formal [3+2+2] cycloaddition of aziridines with two alkynes. This method was applicable to two of the same or different terminal alkynes for the [3+2+2] cycloaddition with unactivated aziridines, and furnished the corresponding azepine derivatives in good yields with good levels of chemo- and regioselectivity. The mechanism was also discussed according to the results of the in situ HRMS and ¹H NMR analysis.

A mild and general alkylation of terminal alkynes with transient σ-alkylpalladium(II) complexes for assembling alkyl-substituted alkynes is described. This method represents a new way to the use of transient σ-alkylpalladium(II) complexes in organic synthesis through 1,2-carboalkynylation of alkenes.

This study describes a new rhodium(III)-catalyzed [3+2] annulation of 5-aryl-2,3-dihydro-1H-pyrroles with internal alkynes using a Cu(OAc)₂ oxidant for building a spirocyclic ring system, which includes the functionalization of an aryl C(sp²)H bond and addition/protonolysis of an alkene CC bond. This method is applicable to a wide range of 5-aryl-2,3-dihydro-1H-pyrroles and internal alkynes, and results in the assembly of the spiro[indene-1,2′-pyrrolidine] architectures in good yields with excellent regioselectivities.

Here we describe the one-pot construction of the pyrrolo[4,3,2-de]quinolinone scaffold by a cascade nitration/cyclization sequence of 1,7-enynes with tBuONO and H₂O. The cascade proceeds through alkene nitration, 1,7-enyne 6-exo-trig cyclization, CH nitrations, and redox cyclization, and exhibits excellent functional group tolerance. The mechanism was investigated using in situ high-resolution mass spectrometry (HR-MS).

The oxidative interception of various σ-alkyl palladium(II) intermediates with additional reagents for the difunctionalization of alkenes is an important research area. A new palladium-catalyzed oxidative difunctionalization reaction of alkenes with α-carbonyl alkyl bromides is described, in which the σ-alkyl palladium(II) intermediate is generated through a Heck insertion and trapped using an aryl C(sp²)H bond. This method can be applied to various α-carbonyl alkyl bromides, including primary, secondary, and tertiary α-bromoalkyl esters, ketones, and amides.

A practical method for the synthesis of azepine derivatives, a typical seven-membered heterocyclic ring system, was developed and involves the use of hexafluoroantimonic acid to catalyze a formal [3+2+2] cycloaddition of aziridines with two alkynes. This method was applicable to two of the same or different terminal alkynes for the [3+2+2] cycloaddition with unactivated aziridines, and furnished the corresponding azepine derivatives in good yields with good levels of chemo- and regioselectivity. The mechanism was also discussed according to the results of the in situ HRMS and ¹H NMR analysis.

Here we describe the one-pot construction of the pyrrolo[4,3,2-de]quinolinone scaffold by a cascade nitration/cyclization sequence of 1,7-enynes with tBuONO and H₂O. The cascade proceeds through alkene nitration, 1,7-enyne 6-exo-trig cyclization, CH nitrations, and redox cyclization, and exhibits excellent functional group tolerance. The mechanism was investigated using in situ high-resolution mass spectrometry (HR-MS).

Copper-catalyzed amidation of acids with formamides or acetamide for the selective synthesis of amides with the aid of 1,4-diazabicyclo[2.2.2]octane as the ligand and tert-butyl hydroperoxide as the oxidant is presented. This method is highly compatible with a wide range of acids, including alkyl acids, aryl acids, α,β-unsaturated acids, and amino acids.

A novel palladium-catalyzed CH oxidation of isoquinoline N-oxides has been developed for regioselectively synthesizing substituted isoquinolines. The method represents the first example of using dialkyl sulfoxides as the alkyl sources for the construction of 1-alkylated isoquinolines. Moreover, the regioselective halogenation of isoquinoline N-oxides is also successful using dihalo sulfoxides as the halide sources.

A novel palladium-catalyzed intramolecular tandem annulation method is presented for the synthesis of 3-[5H-dibenzo[b,e]azepin-11(6H)-ylidene]indolin-2-ones. This method allows the conversion of various 3-[2-(2-iodobenzylamino)aryl]-N-arylpropiolamides to the corresponding 3-[5H-dibenzo[b,e]azepin-11(6H)-ylidene]indolin-2-ones through the diarylation of an alkyne.

A new, general method for the synthesis of phenanthridines has been developed by palladium-catalyzed oxidative remote CH olefination–carboamination–CC bond cleavage tandem reaction. It is noteworthy that alkenes are used as the one-carbon resources for this tandem reaction.

A selective and general route to (E)-1,3-diaryl-prop-1-enes and (E)-3-arylallyl acetates has been developed by palladium-catalyzed Heck-type reactions of allylic esters with arylboronic acids or potassium aryltrifluoroborates. The present method selectively proceeds including β-OAc elimination or β-H elimination on the basis of the boronic acids. Whereas a variety of allylic esters were reacted with arylboronic acids, palladium(II) acetate [Pd(OAc)₂], tetra(n-butyl)ammonium chloride [(n-Bu)₄NCl] and postassium dihydrogen phosphate (KH₂PO₄) to afford the corresponding diarylation products in moderate to good yields, treatment of allylic esters with potassium aryltrifluoroborates furnished the corresponding monoarylation products.