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Photocatalysis holds a pivotal position in modern organic synthesis, capable of inducing novel reactivities under mild and environmentally friendly reaction conditions. However, the merger of photocatalysis and transition-metal-catalyzed asymmetric C-H activation as an efficient and sustainable method for the construction of chiral molecules remains elusive and challenging. Herein, we develop a cobalt-catalyzed enantioselective C-H activation reaction enabled by visible-light photoredox catalysis, providing a synergistic catalytic strategy for the asymmetric dearomatization of indoles with high levels of enantioselectivity (96 % to >99 % ee). Mechanistic studies indicate that the excited photocatalyst was quenched by divalent cobalt species in the presence of Salox ligand, leading to the formation of catalytically active chiral Co(III) complex. Moreover, stoichiometric reactions of cobaltacycle intermediate with indole suggest that the irradiation of visible light also play a critical role in the dearomatization step., (© 2024 Wiley-VCH GmbH.)

Inherently chiral calixarenes have garnered significant attention due to their distinctive properties, yet the development of efficient catalytic asymmetric synthesis methods remains a critical challenge. Herein, we report the asymmetric synthesis of calix[4]arenes featuring inherent or both inherent and axial chirality via a cobalt-catalyzed C-H activation/annulation strategy in high yield with excellent enantio- and diastereoselectivity (up to > 99% ee and > 20:1 dr). Electrooxidation was also suitable for this transformation to obviate the sacrificial metal oxidants, underscoring the environmentally friendly potential of this approach. A key octahedral cobaltacycle intermediate was synthesized and characterized, providing valuable insights into the mode of enantio- and diastereocontrol of this protocol. Noteworthy photoluminescence quantum yields of up to 0.94 were measured, underscoring the potential of these compounds in the domain of organic fluorescent materials., (© 2024 Wiley‐VCH GmbH.)

Transition metal-catalyzed enantioselective C-H carbonylation with carbon monoxide, an essential and easily available C1 feedstock, remains challenging. Here, we disclosed an unprecedented enantioselective C-H carbonylation catalyzed by inexpensive and readily available cobalt(II) salt. The reactions proceed efficiently through desymmetrization, kinetic resolution, and parallel kinetic resolution, affording a broad range of chiral isoindolinones in good yields with excellent enantioselectivities (up to 92 % yield and 99 % ee). The synthetic potential of this method was demonstrated by asymmetric synthesis of biological active compounds, such as (S)-PD172938 and (S)-Pazinaclone. The resulting chiral isoindolinones also serve as chiral ligands in cobalt-catalyzed enantioselective C-H annulation with alkynes to construct phosphorus stereocenter., (© 2024 Wiley-VCH GmbH.)

Highly efficient synthesis of axially chiral biaryl amines through cobalt-catalyzed atroposelective C-H arylation using easily accessible cobalt(II) salt and salicyloxazoline ligand has been reported. This methodology provides a straightforward and sustainable access to a broad range of enantioenriched biaryl-2-amines in good yields (up to 99 %) with excellent enantioselectivities (up to 99 % ee). The synthetic utility of the unprecedented method is highlighted by its scalability and diverse transformations., (© 2023 Wiley-VCH GmbH.)

Metalla-electrocatalyzed C-H oxygenation represents one of the most straightforward and sustainable approaches to access valuable oxygenated molecules. Despite the significant advances, the development of enantioselective electrochemical C-H oxygenation reaction is very challenging and remains elusive. Herein, we described the first electrochemical Co II -catalyzed enantioselective C-H alkoxylation. A broad range of enantioenriched alkoxylated phosphinamides were obtained in good yields with excellent enantioselectivities (up to 98 % yield and >99 % ee). An unusual cobalt(III) alcohol complex was prepared and fully characterized, which was proven to be a key intermediate of this C-H alkoxylation reaction. Mechanistic studies revealed that the oxidation of Co III to Co IV was facilitated by a base and the whole process proceeded through a cobalt(III/IV/II) catalytic cycle., (© 2023 Wiley-VCH GmbH.)

In recent years, the merging of electrosynthesis with 3d metal catalyzed C-H activation has emerged as a sustainable and powerful technique in organic synthesis. Despite the impressive advantages, the development of an enantioselective version remains elusive and poses a daunting challenge. Herein, we report the first electrooxidative cobalt-catalyzed enantio- and regioselective C-H/N-H annulation with olefins using an undivided cell at room temperature (up to 99 % ee). t Bu-Salox, a rationally designed Salox ligand bearing a bulky tert-butyl group at the ortho-position of phenol, was found to be crucial for this asymmetric annulation reaction. A strong cooperative effect between t Bu-Salox and 3,4,5-trichloropyridine enabled the highly enantio- and regioselective C-H annulation with the more challenging α-olefins without secondary bond interactions (up to 96 % ee and 97 : 3 rr). Cyclovoltametric studies, and the preparation, characterization, and transformation of cobaltacycle intermediates shed light on the mechanism of this reaction., (© 2023 Wiley-VCH GmbH.)

The past decade has witnessed a rapid progress in asymmetric C-H activation. However, the enantioselective C-H alkoxylation and amination with alcohols and free amines remains elusive. Herein, we disclose the first enantioselective dehydrogenative C-H alkoxylation and amination enabled by a simple cobalt/salicyloxazoline (Salox) catalysis. The use of cheap and readily available cobalt(II) salts as catalysts and Saloxs as chiral ligands provides an efficient method to access P-stereogenic compounds in excellent enantioselectivities (up to >99 % ee). The practicality of this protocol is demonstrated by gram-scale preparation and further derivatizations of the resulting P-stereogenic phosphinamides, which offering a flexible asymmetric alternative to access P-stereogenic mono- and diphosphine chiral ligands. Preliminary mechanistic studies on the enantioselective C-H alkoxylation reaction suggest that a cobalt(III/IV/II) catalytic cycle might be involved., (© 2022 Wiley-VCH GmbH.)

Previous methods on Co III -catalyzed asymmetric C-H activation rely on the use of tailor-made cyclopentadienyl-ligated Co III complexes, which require lengthy steps for the preparation. Herein, we report an unprecedented enantioselective C-H functionalization enabled by a simple cobalt/salicyloxazoline (Salox) catalysis. The chiral Salox ligands can be easily prepared in one step from salicylonitrile and chiral amino alcohols. A broad range of P-stereogenic compounds were synthesized in high yields with excellent enantioselectivities (45 examples, up to 99 % yield and >99 % ee). The isolation and characterization of several intermediates provided insights into the generation of active catalytic cobalt species, the action of Salox, and the mode of stereocontrol., (© 2022 Wiley-VCH GmbH.)

The development of innovative synthetic polymer systems to overcome the trade-offs between the polymer's depolymerizability and performance properties is in high demand for advanced material applications and sustainable development. In this contribution, we prepared a class of aromatic cyclic esters (M1-M5) from thiosalicylic acid and epoxides by facile one-pot synthesis. Ring-opening polymerization of Ms afforded aromatic polyesters P(M)s with high molecular weights and narrow dispersities. The physical and mechanical properties of P(M)s can be modulated by stereocomplexation and regulation of the side-chain flexibility of the polymers, ultimately achieving high-performance properties such as high thermal stability and crystallinity (T m up to 209 °C), as well as polyolefin-like high mechanical strength, ductility, and toughness. Furthermore, the functionalizable moieties of P(M)s have driven a wide array of post-polymerization modifications toward access to value-added materials. More importantly, the P(M)s were able to selectively depolymerize into monomers in excellent yields, thus establishing its circular life cycle., (© 2022 Wiley-VCH GmbH.)