Terpenoids are the largest and diverse family of natural secondary metabolites that have attracted more attention from chemists and pharmacologists for their intriguing skeletons and broad biological activities, including anti-inflammatory, antitumoral, antimicrobial, and anti-viral effects. Based on the previous reviews, we did a comprehensive summary of recent advances of bioactive terpenoids, focusing on their intriguing structural features and promising biological activities, covering the literatures from 2020 to 2023. In this review, 543 terpenoids with remarkable chemical architectures and biological properties are classified as monoterpenoids (7), sesquiterpenoids (142), diterpenoids (129), sesterterpenoids (24), triterpenoids (52), meroterpenoids (167), and miscellaneous terpenoids (14), that were isolated from terrestrial and marine resources. This review would provide a reference for researchers to rapidly discover the interesting terpenoids for further study as promising drug leads

Salimabromide, a unique and scarce marine tetracyclic polyketide, was synthesized in both racemic and optically active forms. A novel carboxylic acid-directed method for tandem oxidative difunctionalization of olefins was developed, whereby the formation of bridged butyrolactone and enone moieties occurs concurrently. Density functional theory (DFT) calculations indicate that this reaction follows a [3+2] process rather than the [2+2] process. In the meantime, the distinctive benzo-fused [4.3.1] carbon skeleton and highly hin-dered vicinal quaternary stereocentres were simultaneously constructed through a challenging intramolecular Giese-Baran radical cyclization. Furthermore, deuterium kinetic isotopic effects were utilized to enhance the efficacy of this pivotal step. This represents a new illustration of the application of kinetic isotope effects in natural product synthesis. Then, short asymmetric syntheses of (+)-salimabromide (13 or 15 steps) was accomplished by combing this method with rhodium-catalyzed enantioselective hydrogena-tion of a cycloheptenone derivative (97% ee) or conjugate addition of an aryl boronic acid with 2-cyclohepten-1-one (> 99% ee).

A design strategy towards stable fluorenyl radicals (FRs) is established by introducing donor-π-radical (D-π-R) conjugation between amine N atoms and FR centers through phenyl or 9-anthryl moieties. Four FRs with or without N atom containing protecting groups were designed and synthesized for comparison. X-ray crystallographic analysis displayed planar fluorenyl skeletons of CDP-FR and MA-FR, which form large dihedral angles with protecting groups. Even though, the increased bond-order of C-C and C-N bond be-tween radical center and N atoms by Wiberg bond analysis of all FRs confirmed the D-π-R conjugation. Time-dependent DFT calcula-tions based on frontier molecular orbital analysis further revealed the contribution of D-π-R structures as donor-acceptor effect on the lowest energy absorptions of carbazole and diphenylamine substituted CDP-FR and DPAA-FR. Therefore, beneficial from D-π-R conjugations, CDP-FR and DPAA-FR showed better photo-stability than TP-FR and MA-FR. Our study here provides a new strategy to design and synthesize persistent stable monoradicals.

The present work prepared a copper N-heterocyclic carbene complex that could be used in catalyzing the homogeneous hydrogenation of carboxylic acid with ammonia borane (hydrogen source) to synthesize primary alcohols. Various aromatic and aliphatic carboxylic acids with diverse functional groups were transformed to respective alcohols in moderate to high yields. The process can be easily scaled up (TON up to 14545) and exhibit a high compatibility with different sensitive functional groups, including fluorine, chlorine, bromine, iodine, hydroxyl, cyano and nitro groups. IMesCuCl/NH3·BH3 combination can selectively reduce aromatic and aliphatic esters. Mechanistic studies indicate that Cu-H species produced in situ are the active intermediates.

Poly-NHC-based organometallic assemblies 3-PF6, 3-SbF6 and 3-OTf were obtained and verified by NMR spectroscopy, ESI mass spec-trometry and single-crystal X-ray diffraction analyses. Controllable structural interconversion was observed between the poly-NHC-based organometallic assemblies and their self-aggregated dimers in solution affected by concentration, solvent and metal ion. 1H NMR spectra of assembly 3-PF6 in CD3CN at different concentrations demonstrated controllable structural interconversion, and 19F NMR spectrum of assembly 3-PF6 at high concentration further evidenced the presence of the free hexafluorophosphate anion and en-capsulated hexafluorophosphate anion for its two sets of signals. In addition, single-crystal X-ray diffraction analysis provided clear evi-dence that in the solid state, two assemblies 3-PF6 were vertically stuck, forming a self-aggregated dimer with an encapsulated hex-afluorophosphate anion. Investigating the reversible structural interconversion is beneficial for revealing the intrinsic nature on the atom level and paving the way to design the stimuli-responsive functional system.

The frequent occurrence of oil spills not only results in the waste of petroleum resources, but also poses a serious threat to the marine ecological environment. Considering the large amount of crude oils with high viscosity, it is urgent to develop an adsorbent capable of efficiently reducing the viscosity for the cleanup of oil spills. Inspired by the “lotus effect” and “poikilotherm which utilize the solar energy for thermoregulation”, the low surface energy material polydimethylsiloxane (PDMS) and polypyrrole (PPy) were loaded over the island nonwoven fabric to fabricate a novel crude oil adsorbent material. Wherein, the fluorine-free PDMS was used to hydrophobically modify the nonwoven fabric, endowing it with excellent oil-water separation performance, with a separation efficiency of up to 95%. After 10 cycles, the separation efficiency of PPy/PDMS modified nonwoven fabric (PPy/PDMS@NF) was still above 90%, demonstrating superior recyclability. In addition, the PPy/PDMS@NF possessed the self-cleaning capabilities. Under one sun illumination (1.0 kW/m2), the surface temperature of the PPy/PDMS@NF reached to 60.7 ℃, and its adsorption capacity for high-viscosity crude oil reached to 7 gcrude oil/gsorbent. Thanks to its environmental friendliness and excellent adsorption capacity, this work provides a new option for dealing with the high-viscosity marine oil spill.

The first catalytic asymmetric total synthesis of (+)-propolisbenzofuran B, enabled by a highly enantioselective rhodium-catalyzed hy-drogenation of a tetrasubstituted olefin, was described. Other noteworthy aspects include the construction of the central hydrodiben-zo[b,d]furan core through a sequence of Zn(II)-mediated regioselective benzofuran formation and Dieckmann condensation, as well as C-H oxidations, involving a visible light-induced Fe(III)-catalyzed benzylic C(sp3)-H oxidation. Additionally, the absolute configuration was confirmed by X-ray analysis of a carbonate intermediate.

Polycatenane gels have attracted extensive attention due to their high degree of freedom and mobility. However, the synthesis of poly[2]catenane gels reported to date all rely on the polymer as the backbone. Herein, we prepared poly[2]catenane gels based on entirely sequential assembly of small molecules. Monomer M1 with two unclosed rings was first prepared, which self-assembled to form supramolecular polymers(SPs) via hydrogen bonding and π-π interactions. Upon adding small molecule monomers M2 and M3 with aldehyde groups, ring closing of SPs occurred due to the amino groups in the SPs reacted with M2 to form imine bonds. In addition, M3, which has twice the number of aldehyde groups as M2, enabled SPs to ring-close, causing the proceeding of crosslinking process at the same time. Thus linear SPs were transformed into poly[2]catenane gel networks. Due to the presence of hydrogen bonds in the poly[2]catenane gel, the gel also possessed stimulus responsiveness and self-healing properties.

Four polycyclic ten-membered lactones possessing unprecedented 10/6/5 tricyclic ring skeleton, named eutypetides A−D (1−4), and an intriguing polyketide containing a hexahydroisobenzofuran-1(3H)-one motif, named eutypetide E (5) were isolated from the ma-rine-derived fungus Eutypella sp. F0219, together with three new related biosynthetic polyketides eutypetides F−H (6−8). The abso-lute configurations of 1−5 were unequivocally determined by single-crystal X-ray diffraction analyses (Cu Kα), and electronic circular dichroism (ECD) calculations. Eutypetides G (7) showed remarkable anti-inflammatory activity and could reduce the mRNA expres-sion of proinflammatory cytokines IL-1β, IL-6, TNF-α, and iNOS induced by LPS. Most notably, compounds 1, 2, and 5 were formed bi-ogenetically from 6−8 via the key intramolecular [4+2] cycloaddition, respectively.

How to obtain organic electro-optic materials with large electro-optic coefficients, high glass transition temperature, and good optical transparency remains a challenge in this field. To solve this problem, we introduce groups that can undergo Huisgen cycloaddition reactions into the donor and electron bridge of chromophores with large hyperpolarizability using tetrahydroquinoline as the donor. Binary cross-linkable chromophores TLD1-2 with CF3-TCF as the acceptor and chromophores TLD3-4 with 5Fph-TCF as the acceptor were synthesized. After poling and crosslinking, the Tg of TLD1/TLD2 and TLD3/TLD4 were raised to 152 and 174 °C, respectively. The electro-optical coefficients of chromophores TLD1/TLD2 and TLD3/TLD4 were as high as 312 pm/V and 287 pm/V, respectively. The long-term alignment stability test showed that after being left at 85 °C for 500 hours, the cross-linked film TLD3/TLD4 can still maintain more than 98% of the original electro-optical coefficient value, which is higher than that of TLD1/TLD2 (93%). The chromophore TLD3-4 exhibited much blue-shifted maximum absorption wavelengths (~40nm) compared to TLD1-2 which was beneficial for reducing optical loss in the device. The combination of high electro-optic coefficient, strong stability, and excellent optical transparency makes the TLD series of binary cross-linked materials very promising for practical high-performance electro-optic devices.

As one of the famous traditional Chinese herbal medicines, Fritillariae Cirrhosae Bulbus (FCB) is widely used in the prevention and treatment of respiratory diseases and has best curative effect among the known fritillarias medicinal. Due to the variety, complex sources, similar appearance and shape, it is difficult to distinguish FCB with high curative effect (h-FCB) from other common fritillarias (c-FCB) in the market. In this paper, a very simple chemiresistor is used to identify FCB from three commonly used fritillarias drugs. The sensors are fabricated by anisotropic electrically conductive Metal-organic framework (cMOF) thin film Cu3(HHTP)2 (Cu-HHTP[001] and Cu-HHTP[100]) as active materials owing to their ability to detect specific groups of volatile organic compounds (volatolomics) as the functional motifs of chemiresistor. As a result, the sensors show orientation-dependence identification ability to FCB. Cu-HHTP[001]-based sensor shows the highest response (344.17%) to 0.5 g h-FCB powder volatiles among its three other c-FCB which is much higher than Cu-HHTP[100] (135.50%). Ultimately, Cu-HHTP[001] can realize the identification of FCB with an accuracy of 97.2% in a simple and real-time manner.

Imbalance in the levels of ascorbic acid (AA) can pose a risk to human health. Therefore, it’s essential to establish an accurate method for the detection of AA. In this work, a novel N-doped carbon composite (MnOx@NC) with dual enzyme-like activities to detect AA was prepared by calcination of Mn-MOF containing H3TTPCA ligand. Interestingly, the •O2− that leads to its oxidase-like activity was not formed by dissolved oxygen, but came from the synergistic effect of lattice oxygen generated by calcination and the transformation of MnⅡ/MnⅢ/MnⅣ, and the presence of H2O2 provided much •OH, which cause its peroxidase-like activity. Meanwhile, the residual N element came from H3TTPCA ligand assisted the catalytic process. Accordingly, a dual-signal sensing platform and smartphone-assisted recognition for detection of AA was developed and a colorimetric sensor array was established to distinguish three antioxidants. This work also demonstrates considerable promise for the detection of AA in authentic pharmaceuticals.

Rapid dynamics and remarkable proton conduction induced by confined water in nanospaces have attracted much attentions from researchers, which is crucial for advancing the development of innovative proton conductors and deepening comprehension of proton and water transport mechanisms within biological systems. In this aspect, carbon nanotubes (CNTs) are frequently employed as a research platform. However, they possess certain limitations, such as their inherent electronic conductivity and extreme hydrophobicity, which can impede the accurate assessment and precise regulation of proton conduction. We herein prepared two 2D COFs with different hydrophilic fragment, and obtains maximum acid-free proton conductivity of 3.04×10-4 S cm-1 at 70 °C and 100% RH with Grotthuss type activation energy of 0.14 eV. This is mainly due to that the water molecules in the center of channel form strong hydrogen bonds, enhancing proton dissociation and guiding fast directional diffusion.

With protoescigenin as starting material and through orchestrated application of Yu and Schmidt glyco-sylation protocols, the synthesis of acyl group-free escin derivatives were achieved for the first time. As the undesired non-specific toxicity, originated from the existence of acyl groups on aglycone, prohibits the wide application of escins, the established strategies toward non-acylated protoescigenin-type sap-onins would dramatically ease the access to escin derivatives dispense of acyl groups, thereby speeding up the pace of pharmaceutical use of these valuable compounds.

Optically active phthalides are prevalent in many natural and bioactive products. Herein, a novel dynamic kinetic resolution of iso-benzofuranone derivatives through palladium-catalyzed asymmetric allylic alkylation has been developed to synthesize phthalide de-rivatives bearing vicinal quaternary and tertiary stereocenters with high yields, showing excellent regio-, enantio- and diastereoselec-tivity. Furthermore, gram-scale experiment underwent smoothly and the transformation of product could build a bridged bicyclic skeleton.

A mechanistically distinctive visible-light-promoted metal-free aerobic oxidation of alkenyl silanes with alcohols was disclosed to efficiently construct α-alkoxy ketones under mild conditions. The primary, secondary, and tertiary alcohols could be used as reactants. The protocol could be carried out on a gram-scale. The various derivatizations of products could be conducted. Mechanistic studies indicated the reaction was initiated by single-electron oxidation of the alkenyl silanes.

3,3-disubstituted oxindoles, forming the core of extensive bioactive natural products and drugs, attract tremendous efforts to develop efficient methods for their preparation. Here, a substrate-photosensitive strategy for the selective synthesis of 3-substituted 3-aminooxindoles from N-Boc isatin ketimines irradiated by visible light was reported with high yields and broad functional group compatibility.

Natural products with high oxidation states and complex chemical skeletons exhibit diverse bioactivities due to their unique interactions with biological targets. The high oxidation state is characterized by the presence of multiple oxygen-containing functional groups such as hydroxyl groups, carbonyl groups, and epoxides that are usually tough to construct selectively. In recent years, thanks to the development of efficient strategies and sophisticated methodologies, significant advancements have been made in the total syntheses of highly oxidized natural products (HONPs), which are reviewed herein.