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The enantioselective oxidative cyclizations of γ-alkenyl arylsulfonamides and a δ-alkenyl arylsulfonamide for the synthesis of nitrogen heterocycles are presented. The reactions are catalyzed by chiral copper(II) complexes, and MnO2 is used as the inexpensive stoichiometric oxidant. A variety of five-membered heterocycles and a tetrahydroisoquinoline have been synthesized in good to excellent yields with good to excellent levels of enantioselectivity. This is the first reported copper-catalyzed enantioselective carboamination of alkenes.

Polymorphism and anisotropy are fundamental phenomena of crystalline materials. However, the structure-dependent photoluminescent (PL) anisotropy in polymorphic organic crystals has remained unexplored. Herein, two polymorphic nanocrystals, green-emitting nanorods (PtD-g) and yellow-emitting nanoplates (PtD-y), were obtained from a platinum­(II)−β-diketonate complex. The PtD-y crystals display remarkable PL anisotropy with an anisotropy ratio of up to 0.87 whereas the emission of the PtD-g crystals is nearly unpolarized. The polarization properties are rationalized on the different molecular packing of these crystals. By light-harvesting energy transfer, the PtD-y crystals are successfully used to amplify the emission polarization of a red-emitting platinum acceptor (PtA) doped into the donor crystalline matrix, which is otherwise weakly polarized as pure crystals.

A copper(I)-catalyzed direct transannulation of N-heteroaryl aldehydes or ketones with alkylamines via Csp(3)-H amination has been achieved using molecular oxygen as a sole oxidant. N-Heteroarenes are employed as the amine source. This transformation provides a rapid and concise access to multifunctional imidazo[1,5-a]pyridines.

Selective oxidation, a fundamental organic transformation of critical importance, produces value-added products from simple organic molecules. This process is extensively used to incorporate heteroatoms into carbon-based molecules, where high-valent metal salts, hypervalent halogen reagents, and peroxides are widely used as oxidants. Oxidation reactions are extremely challenging because their selectivity is hard to control and/or they form significant quantities of unwanted waste derived from the stoichiometric oxidants. Undoubtedly, the utilization of green oxidants such as molecular oxygen (O) or internal oxidants provides tunable oxidation abilities and produces no environmentally hazardous byproducts. Thus, synthetic chemists have devoted increasing attention to the utilization of green oxidants to obtain valuable products. Since the first industrial application of noble metal-catalyzed oxidation, i.e., Pd/Cu/O-mediated Wacker oxidation, precious metal-catalyzed organic reactions have undergone significant development in both the laboratory and industry. However, the high cost and considerable toxicity of precious metals compel chemists to explore the catalytic activities of earth-abundant, first-row transition metals. Copper is abundant, easy to utilize, and relatively insensitive to water and air. Controllable access to Cu(0), Cu(I), Cu(II), and Cu(III) oxidation states ensures that copper can be applied as a tunable and multifunctional catalyst. Copper-catalyzed transformations involve single-electron transfer (SET), two-electron processes (TEPs) and even the cooperation of SET and TEPs. More importantly, in Cu/O catalytic systems, ligands, additives, and solvents can tune the oxidation state of copper from Cu(I) to Cu(III). As a result, the development of copper-catalyzed aerobic oxidative reactions is possible and desirable. Progress in these synthetic methods will enable breakthroughs in natural product synthesis, materials science, and bioorganic chemistry. This Account describes our efforts over the last several years to develop copper-catalyzed C-C or C-heteroatom bond formation reactions with oxygen or internal oxidants as the oxidant. We primarily focused on reaction with simple substrates, including cross-couplings, cycloadditions, cyclizations, and condensations. These transformations provide convenient and efficient strategies for constructing multiple bonds, such as C-C/C-O bonds, C-C/C-N bonds, and C-N/C-S bonds, in one pot. Various alkynes, furans, benzofurans, lactones, sulfones, thioethers, and nitrogen-containing heterocyclic compounds were synthesized with high selectivity and atom economy from abundant, commercially available and inexpensive starting materials. These methods were successfully applied to the construction of drug molecules and skeletons of natural products. Additionally, the designed control experiments and serendipitous observations have given us mechanistic insights into copper-catalyzed green oxidation. Uncovering the activity of copper-catalyzed green oxidation involvi...

Due to the fascinating structures and wide applications, porous materials with open frameworks have attracted more and more attentions. Herein, a novel two‐dimensional (2D) halogen‐bonded organic framework (XOF–TPPE) was successfully designed and fabricated by iodonium‐bridged N⋅⋅⋅I+⋅⋅⋅N interactions between pyridyl groups and I+ for the first time. The formation of XOF–TPPE and its linear analogue was monitored by 1H NMR, UV–Vis, X‐ray photoelectron spectroscopy (XPS), IR, SEM, TEM, HRTEM and selected‐area electron diffraction (SAED). The structural model of XOF–TPPE was established based on powder X‐ray diffraction (PXRD) data and theoretical simulations. Significantly, synchrotron small‐angle X‐ray scattering (SAXS), DLS and UV–Vis spectroscopy experiments suggested that XOF–TPPE still maintains a stable 2D framework structure in solutions. This research opens up a novel avenue for the development of organic frameworks materials, and may bring new promising applications for the field of porous materials.

Polyethylene terephthalate (PET) is among the most extensively produced plastics, but huge amounts of PET wastes that have accumulated in the environment have become a serious threat to the ecosystem. Applying PET hydrolytic enzymes to depolymerize PET is an attractive measure to manage PET pollution, and searching for more effective enzymes is a prerequisite to achieve this goal. A thermostable cutinase that originates from the leaf-branch compost termed ICCG is the most effective PET hydrolase reported so far. Here, we illustrated the crystal structure of ICCG in complex with the PET analogue, mono­(2-hydroxyethyl)­terephthalic acid, to reveal the enzyme–substrate interaction network. Furthermore, we applied structure-based engineering to modify ICCG and screened for variants that exhibit higher efficacy than the parental enzyme. As a result, several variants with the measured melting temperature approaching 99 °C and elevated PET hydrolytic activity were obtained. Finally, crystallographic analyses were performed to reveal the structural stabilization effects mediated by the introduced mutations. These results are of importance in the context of understanding the mechanism of action of the thermostable PET hydrolytic enzyme and shall be beneficial to the development of PET biodegradation platforms.

An unusual cobalt(III)-catalyzed cross-coupling/cyclization of aryl C−H bonds of N-nitrosoanilines with α-diazoβ-ketoesters has been achieved. This protocol features a unique combination of Csp 2 -H activation/Wolff rearrangement process, allowing for the rapid assembly of quaternary 2-oxindoles. The empirical evidence and density functional theory (DFT) calculations reveal the trapping process of transient acceptor ketene intermediates by cobalt metallocycles.