Chinese Journal of Chemistry最新文献

Herein, we report a rare example of three-component net-oxidative sulfonylation of a SO₂ surrogate with an oxidatively activated radical precursor under mild and metal- and external-oxidant-free conditions. The mildness and sustainability of the reaction are enabled by photoelectrocatalysis, and 3-aza-1,5-dienes, organotrifluoroborates and 1,4-diazabicyclo[2.2.2]octane bis(sulfur dioxide) adduct (DABSO) undergo sulfonylative cyclization to afford sulfono 4-pyrrolin-2-ones in an atom-economical manner with a broad substrate scope and good functional-group tolerance. The protocol is amenable to the late-stage diversification of complex molecular architectures as well as the gram-scale synthesis. Sunlight could be used as the light source, and the reaction could be conducted in an all-solar mode using a commercially available photovoltaic panel to generate electricity in situ. Mechanistic studies reveal that the in situ generated 1,4-diazabicyclo[2.2.2]octane (DABCO), which was generally innocent in previous reactions, functions as an electron shuttle between the photocatalytic cycle and the reactants.

Hydrazine hydrate (DH) is a widely used chemical agent, but it is highly toxic. Thus, the development of low-cost and easy-to-prepare materials for the detection and adsorption of DH is very significant. Herein, a novel and easy-to-prepare supramolecular smart material based on bisquinoline-functionalized naphthalene diimide (DQ8) has been designed and synthesized. In the DQ8, the synergistic effect between quinoline and naphthalene diimide groups has been employed to improve the selectivity and sensitivity for binding of DH. The DQ8-based crystalline porous material (DQ8-CPM) can simultaneously detect and adsorb DH and produce noticeable fluorescence color changes after adsorption of DH vapor. More significantly, the DQ8-CPM shows nice recycling performance on DH detection and adsorption. Meanwhile, a smart gel based on DQ8 (DQ8-G) shows multi-channel response for DH through color, fluorescence, and state changes. The DQ8 shows high selectivity and sensitivity for DH. The detection limit of DQ8 for DH is 8.6 × 10^–7 mol/L. According to the investigation of the DH binding and response mechanism, the synergistic effect between quinoline and naphthalene diimide groups plays an important role in the DH response process. It's a simple and feasible way to develop materials for detection and adsorption of DH through synergistic effects.

Crystalline materials with diastereomerism serve as ideal prototypes for investigating the influence of coordination environments on chemophysical properties. In this study, we synthesized a pair of axial-equatorial isomers [Co(II)(HB(tim^tBu)₃)(cis-dppen)](BF₄)·solv ([HB(tim^tBu)₃]⁻ = hydrotris(3-tertbutyl-2-thioxoimidazol-1-yl)borate; cis-dppen = cis-1,2-bis(diphenylphosphino)ethene; solv = 0.5THF·2H₂O and 2H₂O for ax-CoHS₂P₂ and eq-CoHS₂P₂, respectively), by varying the crystallization temperatures. Despite both diastereoisomers adopting distorted square pyramidal geometries, the bidentate cis-dppen ligand chelates to the central Co(II) either in an axial-equatorial or equatorial-equatorial manner, with a boron-hydrogen binding to the metal center. Magnetic studies reveal differences in g-values between these axial-equatorial isomers. X-band electron paramagnetic resonance spectra suggest rapid equilibrium and potential conformational interconversion in response to temperature changes in solution. Magnetic measurements indicate field-induced slow relaxation of magnetization in this low-spin S = 1/2 system, with spin-lattice relaxations dominated by Raman and quantum tunneling of magnetization mechanisms due to the absence of thermally populated excited states.

We described a Yb(OTf)₃ combined with Pybox ligand catalyzed asymmetric [3+3] cycloaddition of N-vinyl cinnamaldehyde nitrones with activated cyclopropanes to prepare various functionalized 1,2-oxazines in 24%—95% yields and 22%—96% ee. Experimental results revealed that the reaction underwent a domino [3+3] cycloaddition, dealkenylation, and aza-1,4-addition in three steps. The chiral 1,2-oxazine could be obtained in gram scales and easily converted into various 1,2-oxazine scaffolds. The present method features broad substrate scope, good functional group compatibility, three-component domino reaction, and asymmetric [3+3] cycloaddition of N-vinyl nitrones with activated cyclopropanes.

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 photocatalyst-free approach for the synthesis of 3,3-disubstituted oxindoles via a substrate-photosensitive strategy under visible light was successfully developed. Preliminary mechanistic studies illustrated that isatin-derived imines can be directly excited by visible light to generate strong oxidant states, facilitating subsequent single-electron transfer (SET) processes with Hantzsch esters to afford the corresponding α-amino radical intermediates. Thus, these α-amino radicals promote the subsequent Giese radical addition or radical/radical cross-coupling reactions to furnish diverse functionalized 3-substituted 3-aminooxindoles in high yields.

Terpenoids are a large and diverse family of secondary metabolites that have gained 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, this review comprehensively summarized recent advances on bioactive terpenoids, focusing on their intriguing structural features and promising biological activities, covering literature from 2020 to 2023. In this review, 532 terpenoids with remarkable chemical architectures and biological properties are classified into sesquiterpenoids (142), diterpenoids (129), sesterterpenoids (24), triterpenoids (52), and meroterpenoids (185), 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.

An efficient transannular cyano migration is reported for gem-dicyano-1,6-diene, which is triggered by the addition of external arylsulfonyl radicals. The overall transformation proceeds through a sequence of intramolecular 5-exo-trig cyclization, suprafacial 1,4-cyano migration, and the capture by H or D atom, leading to the production of valuable polysubstituted cyclopentanes under mild photoredox catalytic conditions. The reaction is adapted to a wide range of sodium (hetero)arylsulfinates, demonstrating good functional group compatibility. This method provides a new protocol for radical-mediated functional group migration.

Polycyclic Tetramate Macrolactams (PoTeMs) are a family of structurally complex natural products with significant bioactivities. Most of the widespread biosynthetic gene clusters (BGCs) of PoTeMs in bacteria remain silent under normal fermentation conditions. Herein, we report the construction of an efficient chassis (306A) to facilitate the heterologous studies of PoTeM BGCs, which reveals a biosynthetic logic for sequential C14 modifications of PoTeMs through characterizing a PoTeM gene cluster (fla) from marine-derived Streptomyces falvogriseus SCSIO 40032. The C14 hydroxylation was mediated by flavin-dependent oxidoreductase FlaB1 when catalyzing the crucial C6—C13 cyclization, which was supported by feeding and ¹⁸O₂ labeling studies; the C14-OH groups in 5/5/6-type PoTeMs are subsequently converted to ketones by the cytochrome P450 enzyme FlaD. The FlaD homologs FtdF and SSHG_05717 were assayed to show similar functions as FlaD. Besides, the crystal structure of pactamide N (5) provides a critical reference for determining the absolute configuration of 5/5/6-type PoTeMs lacking C14 modifications. This study not only affords an efficient chassis for studying silent PoTeM BGCs, but also provides insights into the biosynthetic logic for C14 oxidative modifications of predominant 5/5- and 5/5/6-type PoTeMs.