C-N Axially Chiral Heterobiaryl Isoquinolinone Skeletons Construction via Cobalt-Catalyzed Atroposelective C-H Activation/Annulation.

Herein, the atroposelective construction of isoquinolinones bearing a C-N chiral axis has been successfully developed via a Co-catalyzed C-H bond activation and annulation process. This conversion can be effectively carried out in an environmentally friendly oxygen atmosphere to generate the target C-N axially chiral frameworks with excellent reactivities and enantioselectivities (up to >99% ee) in the absence of any additives. Additionally, the current protocol has proved to be an alternative approach for the C-N axial architectures fabrication under electrochemical conditions for cobalt/Salox catalysis, and this strategy allowed the efficient and atom-economical synthesis of various axially chiral isoquinolinones under mild reaction conditions.

Cobalt-catalyzed enantioselective C-H/N-H annulation of aryl sulfonamides with allenes or alkynes: facile access to C-N axially chiral sultams.

Herein we report a cobalt-catalyzed enantioselective C-H/N-H annulation of aryl sulfonamides with allenes and alkynes, using either chemical or electrochemical oxidation. By using O2 as the oxidant, the annulation with allenes proceeds efficiently with a low catalyst/ligand loading of 5 mol% and tolerates a wide range of allenes, including 2,3-butadienoate, allenylphosphonate, and phenylallene, resulting in C-N axially chiral sultams with high enantio-, regio-, and position selectivities. The annulation with alkynes also exhibits excellent enantiocontrol (up to >99% ee) with a variety of functional aryl sulfonamides, and internal and terminal alkynes. Furthermore, electrochemical oxidative C-H/N-H annulation with alkynes is achieved in a simple undivided cell, demonstrating the versatility and robustness of the cobalt/Salox system. The gram-scale synthesis and asymmetric catalysis further highlight the practical utility of this method.

C-N Axially Chiral Heterobiaryl Skeletons Construction via Cobalt-Catalyzed Atroposelective Annulation.

Herein, the atroposelective construction of five-six heterobiaryl skeleton-based C-N chiral axis has been successfully accomplished via a Co-catalyzed C-H bond activation and annulation process, in which the isonitrile was employed as the C1 source and the 8-aminoquinoline moiety served as both directing group and integral part of C-N atropisomers, respectively. This conversion can be effectively carried out in an environmentally friendly oxygen atmosphere, generating the target axial heterobiaryls with excellent reactivities and enantioselectivities (up to >99% ee) in the absence of any additives, and the obtained 3-iminoisoindolinone products with a five membered N-heterocycle exhibit high atropostability. Additionally, the C-N axially chiral monophosphine backbones derived from this protocol possess the potential to become an alternative ligand platform.

Nickel-Catalyzed anti-Markovnikov Hydrodifluoroalkylation of Unactivated Alkenes.

An efficient Ni-catalyzed hydrodifluoroalkylation of unactivated alkenes with bromodifluoroacetate by using PhSiH3 as hydride source was developed. The transformation affords aliphatic difluorides with anti-Markovnikov regioselectivity. A wide range of highly remote alkenes, simple alkenes, drug molecules, commercially available CF2 precursors, and even nonfluorinated substrates are competent in this reaction under mild conditions, demonstrating the practicability of the strategy. Moreover, mechanistic studies indicated that the difluoroalkyl radical might be a key intermediate to this transformation.

Directed Cobalt-Catalyzed C-H Activation to Form C-C and C-O Bonds in One Pot via Three-Component Coupling.

Herein, we disclose an efficient cobalt-catalyzed three-component coupling of benzamides, diazo compounds, and tert-butyl hydroperoxide, which provides an efficient approach to construct C(sp2)-C(sp3) and C-O bonds in one-pot accompanied with C-H activation. This protocol features low catalyst loading (4 mol %), the avoidance of additives, and excellent functional group compatibility, providing three-component coupling adducts with high yields under mild conditions (up to 88%). Mechanism studies show that the reaction may involve a radical process.

Directed Cobalt-Catalyzed anti-Markovnikov Hydroalkylation of Unactivated Alkenes Enabled by "Co-H" Catalysis.

The earth-abundant cobalt-catalyzed anti-Markovnikov hydroalkylation of unactivated alkenes with oxime esters was achieved by introducing an 8-aminoquinoline directing group on the alkenes. The catalytic system, consisting of commercially available Co(acac)3 and PhMeSiH2, enables the construction of unfunctionalized C(sp3)-C(sp3) bonds and features exclusive anti-Markovnikov selectivity, good functional group tolerance, and the avoidance of an extra ligand, oxidant, or base. Mechanistic insight into this new catalytic system indicates the involvement of both alkyl radical and cobalt hydride intermediates.

Palladium-catalyzed decarbonylative annulation of phthalimides with arynes: direct construction of phenanthridinones.

A novel palladium-catalyzed decarbonylative annulation for the synthesis of phenanthridinones from phthalimides and arynes has been developed. This catalytic system tolerates a broad range of functional groups. Mechanistic experiments demonstrate that the Pd(ii) complex B is the key intermediate, which has been confirmed by X-ray crystallography for the first time.

Palladium-Catalyzed C-N Bond Cleavage of 2 H-Azirines for the Synthesis of Functionalized α-Amido Ketones.

A Pd-catalyzed ring-opening reaction of 2 H-azirines with carboxylic acids was developed. This reaction undergoes nucleophilic addition between 2,3-diaryl-2 H-azirines and carboxylic acids followed by C-N single-bond cleavage and a subsequent thermal rearrangement. This method enables the rapid construction of valuable α-amido ketone derivatives with high atomic efficiency and superb functional group tolerance.

A high-activity cobalt-based MOF catalyst for [2 + 2 + 2] cycloaddition of diynes and alkynes: insights into alkyne affinity and selectivity control.

This work develops a highly efficient metal-organic framework (MOF) catalyst for the straightforward synthesis of functionalized benzenes via [2 + 2 + 2] cycloaddition. As efficient cooperative catalyst for such reactions, Co-MOF-1, shows great sustainability and efficiency. This new catalytic system can lead to the generation of a series of structurally diverse benzenes in good to excellent yields (up to 95%).