A novel and eco-friendly electrochemical activation of trifluoromethyl thianthrenium triflate (TT–CF 3 +OTf −) for trifluoromethylation of imidazole-fused heteroaromatic compounds was established. This method involves the direct electrolysis of TT–CF 3 +OTf − without the requirement of external oxidants or catalysts, aligning with the principles of green chemistry. A wide range of imidazole-fused heteroaromatic compounds including imidazo[1,2- a]pyridines and benzo[ d]imidazo[2,1- b]thiazoles have been successfully trifluoromethylated using this technique, exhibiting excellent compatibility with various functional groups and a broad substrate scope. Moreover, the method's applicability for one-pot sequential reactions enables the reduction of waste and resource consumption by eliminating the need for intermediate purification steps.
A new, selective Ru(II)-catalyzed alkynylation reaction of isoquinolones, quinazolones and phthalazinones with readily available bromoalkynes has been developed. This reaction enables the selective construction of a new C(sp 2)-C(sp) bond through C—H activation and C—Br functionalization, and offers an effective and selective route to synthesizing highly valuable alkynylated isoquinolone, quinazolone and phthalazinone derivatives with a wide substrate scope and high selectivity.
A novel electrochemical multicomponent cascade reaction of indole-tethered alkenes with CF 3SO 2Na and n-Bu 4NI has been developed, which enables the rapid assembly of spiropyrrolidinyl-oxindoles in good yields. The experimental results and DFT calculations suggest that this reaction proceeds through the oxidation of CF 3SO 2Na, radical coupling with alkene, spirocyclization, oxidation of sulfinate, iodide substitution, and water coupling. This strategy features mild reaction conditions, easy-to-handle reactants, and good chemical yields. This finding not only enriches the research contents of indole-tethered alkenes but also provides a green strategy for the construction of spiropyrrolidinyl-oxindoles compared with the existing methodologies.
Pseudolaric acids are a family of diterpenoid natural products that exhibit a broad spectrum of biological activities. The main structural feature of their framework is a trans-fused perhydroazulene bearing a bridged lactone positioned at the junction of the rings. Herein, we have developed a radical cyclization strategy that allows flexible tuning of the cyclization process through diverse silicon substitutions on the substrates. This strategy can assist in constructing a series of skeletons with structural resemblance to pseudolaric acids and expedites the construction of the bridged lactone. Finally, it facilitates the synthesis of the entire skeletal structure of the pseudolaric acid family of natural products, excluding the B-ring functionalization.
Molecular ferroelastics with the natural features of mechanical flexibility and switchable spontaneous strain have attracted widespread attention in the scientific community due to their potential applications in tunable gratings, flexible memorizers, strain sensors, and intelligent actuators. However, most designs of molecular ferroelastics remain in the stage of blind exploration, posing a challenge to achieve a functional ferroelastic more effectively. Herein, we have successfully obtained a molecular ferroelastic, [Me 2NH(CH 2) 2NH 3](ReO 4) 2 (Me 2NH(CH 2) 2NH 3 = N, N-dimethylethylenediammonium), under the guidance of the mono-/double-protonation strategy. The double-protonated [Me 2NH(CH 2) 2NH 3](ReO 4) 2 undergoes a paraelastic-ferroelastic phase transition with the Aizu notation of 2/ mF at 322 K. Meanwhile, the theoretical calculation and experimental measurement simultaneously show that [Me 2NH(CH 2) 2NH 3](ReO 4) 2 possesses good mechanical flexibility, because its elastic modulus ( E) of 8.26 GPa and hardness ( H) of 0.45 GPa are smaller than the average values of organic crystals ( E of 12.05 GPa and H of 0.5 GPa), which makes it promising to apply in wearable pressure sensors, implantable medical sensors, high-precision tuners, etc. This work further enriches the molecular ferroelastic family and demonstrates that mono-/double-protonation is one of the effective molecular modification strategies for designing ferroelastics.
Hierarchically porous materials (HP materials) are believed one of the most hopeful matrix materials because of their distinctive multimodal pore structures and tremendous application potentials in the field of biomedicine. However, green and facile synthesis of hierarchically porous nanomaterials with beneficial water dispersibility and biocompatibility is still a great challenge. Herein, a novel biomimetic strategy is proposed to prepare the cell-tailored double-shelled HPCaCO 3/CaF 2 hollow nanospheres under the mediation of yeast cells. The biomolecules derived from the secretion of yeast cells are used as conditioning and stabilizing agents to control the biosynthesis of the HPCaCO 3/CaF 2 materials, which exhibit excellent water dispersibility and favorable biocompatibility. The double-shelled CaCO 3/CaF 2 nanospheres hold hierarchically porous structure and have abundant pore channel and large specific surface area, showing high drug-loading and a prolonged drug sustainable release profile by the pore-by-pore diffusion pattern of the hierarchical pores. Otherwise, the HPCaCO 3 with pH-sensitivity could controllably release drug doxorubicin hydrochloride (DOX) at the acidic tumor microenvironment. Both in vitro and in vivo results demonstrate that HPCaCO 3/CaF 2 has the sustainable pH-sensitive drug release property, showing an enhanced therapeutic effect. Summarily, this study provides a biomimetic strategy to synthesize the hierarchically porous double-shelled hollow nanomaterials for applying in sustainable drug delivery system.
Herein, we present a method for the homogeneous hydrogenation of nitroarenes to produce anilines using low catalyst loading (1 mo%) of copper N-heterocyclic carbene complexes as the catalyst and ammonia borane as the source of hydrogen. A wide range of nitroarenes, featuring diverse functional groups, were selectively transformed into their corresponding primary aromatic amines with high yields. This process can be readily scaled up and exhibits compatibility with various sensitive functional groups, including halogen, trifluoromethyl, aminomethyl, alkenyl, cyano, ester, amide, and hydroxyl. Notably, this catalytic methodology finds application in the synthesis of essential drug compounds. Mechanistic investigations suggest that the in-situ-generated Cu-H species may serve as active intermediates, with reduction pathways involving species such as azobenzene, 1,2-diphenylhydrazine, nitrosobenzene, and N-phenylhydroxylamine.
Chemodivergent synthesis of benzofurans and 2,3-dihydrobenzofurans has been realized. Under a reaction system consisting of DBDMH and K 2CO 3 as promotors, controlled conditions enabled the formation of two sets of valuable heterocycles from the tandem transformation of enaminones and salicylaldehydes. The key to success was the identification of the reaction parameters, in which the imine intermediate which was formed by transient halogenation coupling and substitution processes underwent either aldol condensation/annulation or imine hydrolysis/aldol condensation. The additives NH 4Cl or Fe 2(SO 4) 3 controlled the unique selectivity of this reaction. A broad substrate scope of enaminones and salicylaldehydes has been employed in this reaction, demonstrating excellent functional group tolerance and versatility.
Axially chiral biaryls represent the most important class of atropisomers, and they widely exist in natural products and biologically active molecules. They also constitute a unique scaffold for chiral ligands and catalysts in organic synthesis. The development of synthetic methods to obtain such chiral compounds has received widespread attention, among which catalytically atroposelective ring-opening of configurationally labile compounds represents one of the most attractive strategies. Various substrates with strained cyclic structures, such as the renowned Bringmann's lactones, can undergo asymmetric transformation into stable atropisomers. Known advancement primarily relies on metal catalyst combined with well-designed chiral ligands, the approaches utilizing organocatalysis as a critical resolution strategy are notably scarce. In this study, we disclosed a N-heterocyclic carbene (NHC)-catalyzed asymmetric ring-opening reaction of biaryl lactams via direct atroposelective nucleophilic activation. The optimized bulky carbene catalyst ensures that the reaction can proceed under mild conditions, affording the desired product with good to excellent yields and atroposelectivity.
A type of unique azole-hybridized acylhydrazonyl aloe emodins (AAEs) were developed as new antibacterial agents for combating bacterial infections. Some target AAEs showed strong antibacterial activities, especially, tetrazolylthioether AAE 27a exhibited broad antibacterial spectrum with 16—256 folds and 8—64 folds more active antibacterial efficacy than the reference drugs aloe emodin and norfloxacin, respectively. Tetrazolylthioether AAE 27a also gave low hemolysis and cytotoxicity, as well as favorable bioavailability. Preliminary mechanism explorations revealed that tetrazolylthioether AAE 27a could cause bacterial membrane depolarization and damage the cell membrane, resulting in nucleic acid leakage. Moreover, compound 27a could intercalate into DNA to impede its replication and form supramolecular 27a-DNA gyrase complex to disturb the function of DNA gyrase. These findings would provide valuable insights for the further exploration of azolyl acylhydrazonyl aloe emodins as new potential antibacterial candidates.
The first successful organic photovoltaic device was reported by Tang with a PCE of about 1% in a bilayer device. Because the short exciton diffusion length, the PCE of bilayer devices is rather lower. In 1995, Heeger introduced the concept of bulk heterojunction (BHJ) organic solar cells. These cells consist of a unique bicontinuous interpenetrating network of donor and acceptor materials, creating large interfacial areas that facilitate efficient exciton dissociation. Since then, the BHJ structure has become the standard architecture for OSCs. The PCBM, synthesized by Wudl, is the most common acceptor material in the era of fullerene OSCs. The design rules for polymer donors should be compatible with the properties of PCBM. Yu reported a family of narrow bandgap D-A copolymers called PTB, which have shown high efficiency and success in the fullerene OSCs. Due to the limited visible light absorption and morphological instability of fullerene, there has been a significant increase in research on non-fullerene electron acceptors. Zhan created a groundbreaking non-fullerene electron acceptor ITIC, which is the beginning of a new era for non-fullerene OSCs. Later, Zou developed high-performance narrow-bandgap Y6, which significantly boosted the efficiency of OSCs to over 19%. In non-fullerene OSCs, the most commonly used polymer donors are PM6 and D18, which were developed by Hou and Ding.
Biological cells exhibit diverse phenomena induced through linking of chemical reactions of molecules and solid surface contact. It is then a significant topic in the field of chemistry to study phenomena induced through this linking using synthetic systems, which can promote our understanding of biological phenomena and can be applied to the development of novel functions. Silica nanoparticles (SNPs), which are synthetic inorganic materials, are attractive for such purposes, because of their following characteristics: they can adsorb large amounts of molecules on their surfaces, they can aggregate through contact between SNPs as well as contact between molecules and SNPs, and the molecules can be easily removed from solutions by precipitation. The contact of SNP surfaces with molecules then affects chemical reactions of molecules and also behaviors of SNPs. This article describes systems derived from synthetic helical molecules and SNPs, which exhibit notable phenomena including selective adsorption and molecular recognition, equilibrium shift, step kinetics with induction period, precipitation with flow and sweeping, and disaggregation and desorption by sonication, in which the high affinity of helical molecules with SNP surfaces plays important roles. Mechanistic models that explain the phenomena are provided. Possible applications are also discussed, including the separation of molecules, capture of intermediates, the storage and release of molecules, equilibrium shift, clocking, and the translation of mechanical stimulations into chemical reactions.