Latest ArticlesChiral 1,2,3,4-tetrahydro-1,5-naphthyridines are frequently encountered in many bioactive compounds. However, the methods for their asymmetric synthesis are quite limited. Herein, we developed a straightforward and efficient route to enantioenriched tetrahydro-1,5-naphthyridines from pyridine derivatives tethered with alkene moieties (34 examples, up to 99% yield, 93% ee). The reaction proceeded via Csp2–H activation pathway initiated by site-selective deprotonation with the assistance of La[N(SiMe3)2]3/PyBox, followed by alkene insertion into the resulting La-aryl bond. The potential utility of the current method in organic synthesis was highlighted by scale-up synthesis of chiral product and its further transformations. Moreover, some of the products show a pronounced inhibitory effect on A549 cell activity. In addition, experimental studies and DFT calculations were carried out to elucidate the origin of enantiocontrol.
A kind of inherently chiral molecular barrels were efficiently constructed by a directional cascade hooping strategy. This strategy involves the anchoring of three nonsymmetric connecting arms onto a cap-dissymmetric bis(tetraoxacalix[2]arene[2]triazine) cage core, followed by hooping via imine condensation and reduction to afford the target molecular barrels with well-defined connectivity. The precise and high-yielding synthesis stems from both the bidirectional Ctriazine-N bond flipping dynamics and the reversible nature of imine formation. The molecular barrels comprise a bis(tetraoxacalix[2]arene[2]triazine) core encircled by a 72-membered loop, forming three fan-shaped cavities with inherent chirality and multiple endo-functionalized sites. The existence of multiple diastereoisomeric conformers due to the restricted Ctriazine-N bond flipping by the constrained loop structure was revealed by variable-temperature NMR studies and DFT calculations.
The typical organic perylenetetracarboxylate (PTC) luminophore suffers from limited bio-application due to its aggregation-caused quenching (ACQ) induced undesirable electrochemiluminescence (ECL) efficiency in aqueous solution. Herein, the ECL emission of PTC was highly improved through the ingenious coordination of PTC (ligand) with Tb3+ (metal ion) to prepare the Tb-PTC metal-organic framework (Tb-PTC MOF), which prevented the π-π stacking and the aggregation of PTC molecules in a homogeneous phase. Moreover, we found that the ECL emission of Tb-PTC MOF was further enhanced by regulating its morphology, pore size and electron transfer ability using different solvents during its synthesis procedure. Notably, under the mixture of DMF, EtOH, and H2O (v/v/v, 1:1:1), a mesoporous Tb-PTC MOF exhibited an outstanding ECL intensity, which may be attributed to two reasons. Firstly, the mesopore and rough surface of Tb-PTC MOF (luminophore) provided abundant active sites and enlarged contact surfaces for S2O82– (coreactant). Secondly, Tb-PTC MOF with higher electron transfer ability could accelerate electron/hole recombination to enhance its ECL emission. Additionally, Tb-PTC MOF with excellent ECL performance was applied as a luminophore to fabricate an ultrasensitive ECL immunosensor for cardiac troponin Ⅰ (cTnI) detection, related to acute myocardial infarction. The constructed ECL immunosensor exhibited a satisfactory linear range (1 fg/mL − 20 ng/mL) and a low detection limit of 0.48 fg/mL. This study provides a new trend for the preparation of PTC-based nanomaterials with highly efficient ECL performance, broadening the scope for sensitive immunoassay in disease diagnosis.
Tertiary N–CF3 compounds have attracted intensive attention due to their great significance in discovery of new lead compounds, however, the synthesis of tertiary diaryl N–CF3 derivatives is still challenging. Herein, we successfully edit diaryl N–H into thiocarbamoyl fluorides with trifluoromethanesulfonyl chloride by use of a PⅢ/PⅤ redox catalyst, leading to the formation of series of diaryl N–CF3 with silver fluoride. In addition, this process is also highly efficient to dialkyl and alkylaryl secondary amines. The mechanism investigation illustrated that the use of hydrosilane is crucial to the success of this transformation. It acts as both terminal reductants to cycle the PⅢ/PⅤ couple and fluoride acceptor to promote the reaction between less reactive amine and thiocarbonyl difluoride intermediate.
The site-selective C(sp3)-H functionalization is of great importance in synthetic chemistry. However, γ-amino C(sp3)-H functionalization of aliphatic amines remains challenging. Herein, we develop an efficient γ-C(sp3)-H acylation of aliphatic amines by cooperative photoredox NHC/Pd catalysis. The process entails the following key steps: (ⅰ) photoinduced palladium-promoted formation of aryl radical, (ⅰ) generation of transient γ-amino alkyl radical through aryl radical-mediated 1,7-HAT, (ⅲ) single-electron oxidation of Breslow enolate intermediate to persistent ketyl radical, and (ⅳ) radical/radical coupling of γ-amino alkyl radical with ketyl radical. The synthetic utility of this γ-amino C(sp3)-H acylation is illustrated by the conversion of readily available aliphatic amines to a diverse collection of γ-aminoketones, which serve as versatile building blocks to enable the synthesis of pyrrolines of interest in medicinal chemistry. The radical mechanism is supported by the results of various control experiments, in situ EPR analysis, radical trapping experiment, and isotopic labeling studies.
Nanobelts have attracted significant attention in both synthetic and supramolecular chemistry due to their distinctive structures and promising applications. However, their synthesis remains challenging due to the high strain inherent in their ribbon-like configurations. A promising approach to mitigate this strain involves incorporating heteroatoms, such as sulfur and oxygen, which not only alleviate strain but also introduce new functionalities. In this study, we report the synthesis of a novel C2-symmetric nanobelt, [7]cyclophenoxathiin ([7]CP), through a multi-step process. The structure of [7]CP was confirmed using NMR, mass spectrometry, and single-crystal X-ray diffraction, revealing a heptagonal frustum-shaped geometry. Host-guest interactions between [7]CP and selected fullerenes were investigated using UV–vis absorption, 1H NMR, and X-ray crystallography. Our findings demonstrate that [7]CP forms 1:1 complexes with fullerenes, exhibiting moderate binding through π−π interactions, with binding constants of 1638, 2534, and 3682 L/mol for C60, C70, and PC61BM, respectively. The reduced cavity size of [7]CP prevents the formation of dimeric complexes observed with [7]cyclophenoxathiin, while still allowing it to function effectively as a molecular container.
Metal-free nanoparticles capable of executing synergistic photothermal therapy (PTT) and photodynamic therapy (PDT) under the action of a single-wavelength laser have garnered considerable attention. Here, a novel type of nitrogen-sulfur co-doped carbon nanoparticles (TG-CNPs) was synthesized from taurine and genipin using a solvothermal method in dimethylformamide. The TG-CNPs, with an average size of approximately 25 nm, demonstrated red and near-infrared absorption/emission in aqueous solution. TG-CNPs exhibited negligible dark cytotoxicity, excellent biocompatibility, and remarkable lysosomal localization ability. Upon 655-nm laser irradiation, TG-CNPs exhibited strong photothermal performance with a photothermal conversion efficiency of 30% along with the efficient generation of superoxide radicals (•O2−). Leveraging the enhanced permeability and retention (EPR) effect, TG-CNPs facilitated passive targeting and accumulation at the tumor site. Notably, following a single round of 655-nm laser treatment, the tumors in the mice were completely eradicated, with no evidence of recurrence observed over the subsequent five months. This study introduces a promising metal-free, heteroatom-doped carbon nanoparticle platform for effective synergistic PTT/PDT in tumor treatment.
Although the incorporation of deuterium has been widely researched, controlled deuterium labelling at precise sites is still very challenging. Herein, efficient catalytic synthesis of deuterated pyrroles is focused, the radical cyclizations of N-propargyl enamines were achieved from photoredox-mediated deuterated water splitting, giving deuterated pyrroles with deuterations at the C(sp2) and C(sp3) precisely. One or two-sites-deuterium incorporation as well as the controllable deuteration label at multi-H/D-exchange-sites, such as a methyl group, have been realized in high selectivity and efficiency via the solvent-controlled divergent deuterations. A halogen effect between solvents and substrates was proposed to initiate different catalytic cycles for the deuterations. The broad tolerance to substrates, the gram scale synthesis under natural sunlight irradiation and its applications in the synthesis of drug analogues further verified their practicality.
A concise asymmetric synthesis of the anti-influenza drug (–)-oseltamivir phosphate (1) has been accomplished in 9 steps with an overall yield of 24%, starting from ethyl propiolate. The key features in this synthesis include an efficient biphasic Pd-catalyzed regioselectively intramolecular Heck-type cyclization to provide access to the highly valued chiral six-membered carbocyclic architecture, a regioselective and diastereoselective nitroso hetero-Diels-Alder reaction to construct the bicyclic oxazine 4 as well as a Cu(OTf)2-mediated regioselective and diastereoselective nucleophilic substitution reaction of bicyclic oxazine 4 with 3-pentanol to yield the trans-1,2-substituted diamino cyclohexyl amyl ether 16 with the correct three contiguous stereocenters. This rapid functionalization of the advanced molecular framework would offer an effective strategy for the asymmetric synthesis of other oseltamivir phosphate analogues.
The intrinsic scintillation property of uranium has recently endowed this heaviest naturally occurring element with new opportunities for X-ray radiation detection and visualization. However, the low radiation stability of most uranium compounds hinders their practical application, particularly in X-ray imaging. Here, we presented a flexible two-dimensional uranium-organic framework (UOF, SCU-334) as an air-stable scintillating material for X-ray detection and, for the first time, a systematic investigation of X-ray imaging in UOFs. Following continuous high dose rate X-ray irradiation exceeding 50 Gy, which equals thousands of chest X-ray diagnoses, SCU-334 retains over 90% of its initial performance, representing a significant improvement over previously reported scintillating UOFs. The upgraded radiation resistance of SCU-334 is attributed to its flexible structure that dissipates energy more efficiently under high-energy particle bombardment through conformation fluctuation and relaxation. This work offers a promising approach to improve the radiation resistance of uranium-based scintillators.
No. 86 Xueyuan South Road, Haidian District, Beijing
010-62662699(Operation and Technical Support)
qkjq@cast.org.cn
Copyright © 2025 China Association for Science and Technology. All rights reserved. For all open access content, the relevant licensing terms apply.
Sponsored by the Office of the Leading Group for Cybersecurity and Informatization of CAST, and supported by Science and Technology Review Publishing House
