Difluoromethylarylation of Alkynes from [Bis(difluoroacetoxy)iodo]benzene: Access to CF2H-Containing Dibenzazepines.

A photoinduced radical difluoromethylarylation via tandem addition-cyclization of alkynes with easily available [bis(difluoroacetoxy)iodo]benzene is accomplished, providing a straightforward and practical route for the construction of difluoromethylated dibenzazepines. Various sensitive functional groups can be compatible under photoinduced conditions. Mechanism investigation reveals that this transformation is initiated by the addition of alkyne with difluoromethyl radical, generated in situ from [bis(difluoroacetoxy)iodo]benzene.

Correction: Recent advances in the direct ß-C(sp2)-H functionalization of enamides.

Correction for 'Recent advances in the direct ß-C(sp2)-H functionalization of enamides' by Tonghao Zhu et al., Org. Biomol. Chem., 2020, DOI: 10.1039/c9ob02649e.

Recent advances in the direct ß-C(sp2)-H functionalization of enamides.

The direct ß-C(sp2)-H functionalization of enamides has attracted increasing attention among the chemical community, due to the diverse biological and pharmaceutical activities of enamides. This review is focused on the recent advances in the direct ß-C(sp2)-H functionalization of enamides, mainly including arylation, alkenylation, alkynylation, alkylation, acylation, sulfonylation, phosphorylation, and others. Additionally, mechanistic features of these transformations are also discussed.

I2/CHP mediated [1 + 1 + 1 + 1] cyclization of aromatic isocyanides with amines to construct 1,3-diazetidine-2,4-diimine derivatives.

An I2/CHP (cumene hydroperoxide) mediated [1 + 1 + 1 + 1] cyclization of aromatic isocyanides with readily accessible amines via the formation 4 new C-N bonds has been developed to construct unsymmetric 1,3-diazetidine-2,4-diimine derivatives under mild conditions.

Metal- and additive-free ß-C(sp2)-H decarboxylative alkylsulfonylation of enamides from phenyliodine(III) dicarboxylates and sulfur dioxide.

A green process for the direct C(sp2)-H decarboxylative alkylsulfonylation of enamides under metal- and additive-free conditions is reported. This reaction employs phenyliodine(III) dicarboxylates as the alkyl radical precursors and DABCO·(SO2)2 as the sulfur dioxide surrogate. Diverse (E)-alkylsulfonyl enamides are generated in moderate to good yields with high stereoselectivity under extremely mild conditions via a radical process. A broad substrate scope and excellent functional group tolerance are presented. Moreover, a cascade alkylsulfonylation/cyclization reaction of N-methacryloyl enamides occurs smoothly, giving rise to various alkylsulfonylated pyrrolidones.

Cobalt-catalyzed oxidative isocyanide insertion to amine-based bisnucleophiles: diverse synthesis of substituted 2-aminobenzimidazoles, 2-aminobenzothiazoles, and 2-aminobenzoxazoles.

Cobalt catalysis: Synthesis of substituted 2-aminobenzimidazoles, 2-aminobenzothiazoles, and 2-aminobenzoxazoles was achieved by using cobalt(II) acetate catalyzed isocyanide insertion to o-diaminobenzene, 2-aminobenzenethiol, and 2-aminophenol derivatives in 1,4-dioxane (see scheme). It was found that the reaction proceeded efficiently to give the desired products in up to 95 % isolated yields by C-N and C-S (O, N) formation in a single step.

Deaminative metal-free reaction of alkenylboronic acids, sodium metabisulfite and Katritzky salts.

A convenient and efficient approach to (E)-alkylsulfonyl olefins via a metal/light-free three-component reaction of alkenylboronic acids, sodium metabisulfite and Katritzky salts is described. This alkylsulfonylation proceeds smoothly with a broad substrate scope, leading to diverse (E)-alkylsulfonyl olefins in moderate to good yields. During the process, excellent functional group tolerance is observed and sodium metabisulfite is used as the source of sulfur dioxide. Mechanistic studies show that the alkyl radical generated in situ from Katritzky salt via a single electron transfer with alkenylboronic acid or DIPEA is the key step for providing an alkyl radical intermediate, which undergoes further alkylsulfonylation with sulfur dioxide.

Directing-Group-Assisted C(sp2)-H Arylsulfonylation from Sulfur Dioxide.

A straightforward and stereoselective preparation of (Z)-ß-alkenyl sulfones through a reaction of N-tosyl acrylamides, 1,4-diazabicyclo[2.2.2]octane-sulfur dioxide, and aryldiazonium tetrafluoroborates under copper catalysis is accomplished. The direct C(sp2)-H arylsulfonylation of acrylamides using sulfur dioxide as the sulfonyl source in the presence of copper trifluoroacetate proceeds smoothly, giving rise to (Z)-ß-alkenyl sulfones in good yields. During the reaction process, excellent regio- and stereoselectivities are observed.

A Pd-catalyzed ring opening coupling reaction of 2,3-allenylic carbonates with cyclopropanols.

A palladium-catalyzed coupling reaction of 2,3-allenylic carbonates with cyclopropanols was developed, affording valuable 1,3-diene products with different functional groups efficiently under mild reaction conditions. Gram scale synthesis was easily conducted with synthetic transformations demonstrated.

Regioselective and Stereoselective Difluoromethylation of Enamides with Difluoromethyltriphenylphosphonium Bromide via Photoredox Catalysis.

A regioselective and stereoselective difluoromethylation of enamides with bench-stable and easily accessible difluoromethyltriphenylphosphonium bromide is described. A broad array of synthetically important and geometrically defined ß-difluoromethylated enamides bearing various functional groups are obtained with up to 91% yield.

3,4-Alkadienyl ketones via the palladium-catalyzed decarboxylative allenylation of 3-oxocarboxylic acids.

In this communication, we report a palladium-catalyzed decarboxylative allenylation of benzyl carbonates and tert-butyl carbonates of 2,3-allenols with 3-oxocarboxylic acids. The reaction provides a new and straightforward approach to 3,4-dienyl ketones under mild conditions.

Synthesis of carbodiimides by I2/CHP-mediated cross-coupling reaction of isocyanides with amines under metal-free conditions.

An I2/CHP-mediated cross-coupling reaction of isocyanides with readily accessible amines via C-N formation is described for carbodiimide synthesis in moderate to excellent yields. This represents a metal-free strategy for a coupling reaction of isocyanides with amines, and it provides an efficient approach for symmetric and unsymmetric functionalized carbodiimide derivative synthesis under mild conditions.

Co(acac)2/O2-mediated oxidative isocyanide insertion with 2-aryl anilines: efficient synthesis of 6-amino phenanthridine derivatives.

A novel and efficient protocol for the creation of 6-amino phenanthridine derivatives by Co(acac)2-catalyzed isocyanide insertion with 2-aryl anilines under an O2 atmosphere via homolytic aromatic substitution (HAS) type C-H functionalization has been developed. This reaction not only proceeds smoothly utilizing O2 as the oxidant but also provides a new approach to construct phenanthridine derivatives utilizing readily available 2-aryl anilines with isocyanides instead of 2-isocyanobiaryls with different radical precursors.

tert-Butyl peroxybenzoate (TBPB)-mediated 2-isocyanobiaryl insertion with 1,4-dioxane: efficient synthesis of 6-alkyl phenanthridines via C(sp3)-H/C(sp2)-H bond functionalization.

An efficient method for the construction of 6-alkyl phenanthridines by tert-butyl peroxybenzoate (TBPB)-mediated 2-isocyanobiaryl insertion with 1,4-dioxane was established. Two new C-C bonds were formed in this reaction via a sequential C(sp(3))-H/C(sp(2))-H bond functionalization under metal-free conditions.