ABSTRACT We report a site‐ and regioselective Heck‐type double arylation of substituted 1,2‐dihydropyridines. This transformation provides access to 2‐substituted 3,6‐diarylated 1,2‐dihydropyridines from readily available dearomatized pyridine derivatives. Two complementary strategies were developed: a direct double arylation approach that rapidly furnishes symmetrically diarylated products and a sequential arylation strategy that enables the controlled introduction of two different aryl groups. Both approaches proceed with generally high selectivity and tolerate different 1,2‐dihydropyridine substrates and aryl iodides. Overall, this study provides a concise entry to highly substituted 1,2‐dihydropyridine scaffolds.
Imido ligands strongly influence high-valent molybdenum olefin-metathesis catalysts, yet their electronic impact remains difficult to quantify. Here, a series of Mo(VI)(NAr)Cl2(OtBuF9)2 pre-catalysts is investigated by 9 5Mo NMR spectroscopy, catalytic testing, and DFT calculations. Within the aryl-imido family, electron-withdrawing substituents give more shielded 9 5Mo isotropic shifts and higher activities in 1-nonene self-metathesis after reduction with 1-methyl-3,6-bis(trimethylsilyl)-1,4-cyclohexadiene, whereas electron-donating substituents show the opposite trend. Shielding-tensor, natural chemical shielding, and molecular-orbital analyses show that this correlation is mainly encoded in sigma 11 through stabilization of the occupied pi(Mo & boxH;NAr) HOMO, which reduces paramagnetic deshielding. Comparison with oxo and tert-butyl-imido analogues reveals that similar 9 5Mo shifts can arise from distinct occupied-orbital manifolds, making tensor, and orbital analyses essential for interpreting 9 5Mo NMR descriptors.
ABSTRACT Sodium‐ion batteries are a cost‐effective and more sustainable alternative to lithium‐ion systems for large‐scale energy storage. Among potential cathode materials, Prussian white (PW) is attractive due to its open framework, high theoretical capacity, and favorable sodium‐ion transport. In this study, we report a continuous‐flow coprecipitation process for the scalable synthesis of high‐sodium‐content PW with controlled composition, crystallinity, and particle size. The system employs a Taylor–Couette reactor with separate ferrocyanide/reductant/acid and FeSO 4 /acid feeds; redox control via Na 2 SO 3 and mild acidification suppresses Prussian blue impurities. Operation at 90°C and ≈ 1 bar with a mean residence time of ≈ 60 min yields monoclinic PW with Na/Fe ratios of 0.81–0.88, median particle sizes (D50) of 6–17 µm, water contents of 10.8–13.2 wt%, and BET surface areas of ≈ 7.7–7.9 m 2 g −1 at space‐time yields of 47–93 g L −1 h −1 . The study addresses the synthesis and materials characterization; electrochemical testing was outside its scope.
ABSTRACT While N‐heterocyclic carbenes (NHCs) have emerged as privileged ligands in organometallic chemistry and homogeneous catalysis, protic variants have remained remarkably underdeveloped despite the potential of proximal N–H sites for cooperative reactivity. Here we synthesized a series of ruthenium(II) complexes [RuCl 2 (cym)(NHC)] containing NHC ligands with varied N─H content (NH, NH 5a , NH, NMe 5b , NMe, NMe 5c ) and ring size (five‐membered 5a–c , six‐membered 6a ; cym = para‐ cymene). NMR spectroscopy and x‐ray diffraction reveal distinct effects of N‐substitution and ring expansion on ligand geometry, N─H⋯Cl hydrogen bonding, and MeCN insertion. In transfer hydrogenation catalysis, the activity follows the trend NMe, NMe > NMe, NH > NH, NH, which mirrors catalyst stability under basic conditions, indicating that catalyst robustness rather than NH‐mediated cooperativity governs transfer hydrogenation activity. Under base‐free conditions, the diprotic NH, NH system leads to competitive H 2 formation, thus diverting hydride transfer away from substrates and emphasizing the relevance of controlling competing hydride transfer pathways.
The growing challenge of antimicrobial resistance has intensified the need for new antimicrobial therapeutics. Hipposudoric acid and norhipposudoric acid, pigments isolated from the skin secretions of Hippopotamus amphibius, are predicted to exhibit antimicrobial activity, but are limited by intrinsic chemical instability and synthetically demanding access. Herein, we report on the design and synthesis of a series of fluorene-based derivatives loosely inspired by the tricyclic framework of the natural products. Preparation of sixteen novel N-alkylated derivatives was accomplished via a series of concise one-step amide N-alkylation reactions. Reaction outcome was noted to be strongly dependent on electronic activation and steric accessibility of the alkyl halide electrophiles, with adjacent electron-withdrawing groups significantly enhancing the efficiency of the N-alkylation reaction. All synthesized compounds exhibited excellent short-term stability under both solution-phase and solid-state storage conditions. Furthermore, in silico ADME evaluation predicted that the entire library complies with Lipinski's rule of five and possesses favorable predicted drug-like properties, including acceptable predicted gastrointestinal absorption and membrane permeability profiles.
