C3 Selective chalcogenation and fluorination of pyridine using classic Zincke imine intermediates

Nature Communications, Год журнала: 2024, Номер 15(1)

Опубликована: Авг. 28, 2024

Regioselective C-H functionalization of pyridines remains a persistent challenge due to their inherent electronically deficient properties. In this report, we present strategy for the selective pyridine C3-H thiolation, selenylation, and fluorination under mild conditions via classic N-2,4-dinitrophenyl Zincke imine intermediates. Radical inhibition trapping experiments, as well DFT theoretical calculations, indicated that thiolation selenylation proceeds through radical addition-elimination pathway, whereas two-electron electrophilic substitution pathway. The pre-installed electron-deficient activating N-DNP group plays crucial positive role, with additional benefit recyclability. practicability protocol was demonstrated in gram-scale synthesis late-stage modification pharmaceutically relevant pyridines.

Язык: Английский

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Advances in Pyridine C – H Functionalizations: Beyond C2 Selectivity

Chemistry - A European Journal, Год журнала: 2024, Номер 31(2)

Опубликована: Ноя. 28, 2024

The pyridine core is a crucial component in numerous FDA-approved drugs and Environmental Protection Agency (EPA) regulated agrochemicals. It also plays significant role ligands for transition metals, alkaloids, catalysts, various organic materials with diverse properties, making it one of the most important structural frameworks. However, despite its significance, direct selective functionalization still relatively underdeveloped due to electron-deficient nature strong coordinating ability nitrogen. Among variety synthetic transformation, C-H bond straightforward atom economical approach it's advantageous late-stage containing drugs. In recent years, innovative strategies regioselective pyridines azines have emerged, offering benefits such as high regioselectivity, mild conditions, enabling transformations that were challenging traditional methods. This review emphasizes latest advancements meta para-C-H through approaches, including phosphonium salts, photocatalytic methods, temporary de-aromatization, Minisci-type reactions, metal-catalyzed activation techniques. We discuss advantages limitations these current methods aim inspire further progress this field.

Язык: Английский

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Iridium/Acid Dual-Catalyzed Enantioselective Aza-ene-type Allylic Alkylation of Nitro Ketene Aminals with Racemic Allylic Alcohols

Organic Letters, Год журнала: 2024, Номер 26(2), С. 508 - 513

Опубликована: Янв. 5, 2024

The enantioselective allylic alkylation of nitro ketene aminals with racemic alcohols was realized by iridium/acid dual catalysis. An allyl group installed on the α-position in a branched-selective manner high efficiency excellent enantioselectivities (93–99% ee). protocol applied to late-stage modification neonicotinoid insecticides, which directly furnished novel analogue good insecticidal activity against Aphis craccivora (LC50 = 6.40 mg/L). On basis control experiment, an aza-ene-type reaction mechanism proposed.

Язык: Английский

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Anchorable Polymers Enabling Ultra‐Thin and Robust Hole‐Transporting Layers for High‐Efficiency Inverted Perovskite Solar Cells

Angewandte Chemie, Год журнала: 2025, Номер unknown

Опубликована: Янв. 9, 2025

Abstract Currently, the development of polymeric hole‐transporting materials (HTMs) lags behind that small‐molecule HTMs in inverted perovskite solar cells (PSCs). A critical challenge is conventional are incapable forming ultra‐thin and conformal coatings like self‐assembly monolayers (SAMs), especially for substrates with rough surface morphology. Herein, we address this by designing anchorable (CP1 to CP5). Specifically, coordinative pyridyl groups introduced as side‐chains on poly‐triarylamine (PTAA) backbone varied contents copolymerization method, resulting chemical interactions between substrates. The strong interaction allows them be processed into ultra‐thin, uniform, robust layers through employing low‐concentration solutions (0.1 mg mL −1 , vs. 2.0–5.0 PTAA), greatly decreasing charge transport losses. Moreover, upon systematically tuning substitution ratio, energy levels, wetting, solution processability, defect passivation capability such simultaneously optimized. Based optimal CP4, achieved highly efficient PSCs power conversion efficiencies (PCEs) up 26.21 %, which par state‐of‐the‐art SAM‐based PSCs. Furthermore, these devices exhibit enhanced stabilities under repeated current–voltage scans reverse bias ageing compared devices.

Язык: Английский

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Synthesis of Imidazole Adducts of BH₃, BF₃, and B₃H₇ and Comparison of Their Nucleophilic Substitution Reaction Activity

Chinese Journal of Chemistry, Год журнала: 2025, Номер unknown

Опубликована: Янв. 27, 2025

Comprehensive Summary N ‐Methylimidazole borane adducts were synthesized and their reactivities with different electrophiles after deprotonation compared. Subsequently, we used the more stable reactive imidazole B 3 H 7 , a multinuclear borane, to generate various C2, C2 benzyl, C2,5‐disubstituted of under mild reaction conditions. Some 2,5‐disubstituted products are usually difficult synthesize directly from molecules. Furthermore, moiety these can be easily removed obtain corresponding imidazoles. The higher reactivity compared imidazoles may attributed σ‐aromaticity or mediated by double hydrogen bonds.

Язык: Английский

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N-Boryl Pyridyl Anion Chemistry

Accounts of Chemical Research, Год журнала: 2025, Номер unknown

Опубликована: Фев. 27, 2025

ConspectusPyridine is a crucial heterocyclic compound in organic chemistry. Typically, the pyridine motif behaves as an N-nucleophile and electron-deficient aromatic ring. Transforming ring into electron-rich system that exhibits reactivity contrary to classical expectations could unveil new opportunities This Account describes approach umpolung of through formation unprecedented N-boryl pyridyl anion (N-BPA) intermediate enables catalysis transformations.In 2017, we discovered 4-phenylpyridine acts efficient catalyst for borylation iodo- bromoarenes using diboron(4) compounds. Mechanistic studies revealed situ N-BPA pyridine/diboron(4)/methoxide reaction pivotal step this transformation. Further investigations showed dual reactivities both strong electron donor potent nucleophile. unique profile has unveiled novel pathways redox catalysis, derivatizations, transformations.Based on electron-donor characteristic anion, have developed catalytic mediated by catalyst. In pyridine/diboron(4)/base system, followed single transfer (SET) substrate with regeneration molecule establishes cycle. single-electron reduction variety substrates employing source. Upon visible-light excitation, transitions its excited state, exhibiting significantly enhanced reductivity. establishment modular photoredox consisting various combinations allow fine-tuning property. Using strategy, performed series challenging reactions, including -electron nonactivated chloro- fluoroarenes, Birch arenes.The nucleophilic character was effectively harnessed facilitate derivatization transformations. By directly quenching situ-generated proton source, practical N-H-1,4-dihydropyridines (DHPs). Bimolecular substitution between alkyl bromide produced 4-alkyl-1,4-DHP, which subsequently releases radical under conditions. process enabled transformation bromides radicals. Employing 4-trifluoromethylpyridine chemistry, resulting undergoes elimination fluoride yield 4-pyridyldifluoromethyl nucleophile, then reacts electrophiles realize defluorinative functionalization forge pyridyldifluoromethyl Alternatively, when 4-perfluoroalkylthiopyridine employed, similar occurred form perfluoroalkyl demonstrating perfluoroalkylation reagent offers distinct advantages over traditional reagents.The described provide insights We anticipate these findings will inspire further exploration mechanisms related

Язык: Английский

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Unlocking redox-active reactivity of dearomatized pyridines with photochemistry toward meta-C–H functionalization of pyridines

Chem Catalysis, Год журнала: 2025, Номер unknown, С. 101326 - 101326

Опубликована: Март 1, 2025

Язык: Английский

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Ligand-Controlled Regioselective Dearomative Vicinal and Conjugate Hydroboration of Quinolines

Journal of the American Chemical Society, Год журнала: 2025, Номер unknown

Опубликована: Март 27, 2025

A dearomative strategy to regioselectively modify arenes using a "diene" synthon within aromatic rings provides access highly functionalized heterocycles from abundant feedstocks and represents an alternative synthetic approach besides traditional cross-coupling C-H functionalization methodologies. In this study, we present efficient method for selectively introducing boron onto quinolines through hydroboration easily accessible stable phosphine-ligated borane complexes. The vicinal 5,6- conjugate 5,8-hydroborated products could be obtained by modifying the phosphine ligand. Drawing inspiration diverse organoboron transformations, these building blocks were diversified range of downstream functionalizations, providing modular pathways skeletal modifications variety challenging heterocycles.

Язык: Английский

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C3–H Trifluoroacetylation of Quinolines and Pyridines: Access to Heteroaryl Ketones, Carboxylic Acids, and Amides

Organic Letters, Год журнала: 2025, Номер unknown

Опубликована: Май 22, 2025

Despite extensive synthetic endeavors, achieving direct C3-H trifluoroacetylation in quinolines/pyridines continues to pose significant challenges. We report a protocol for of quinolines and pyridines under transition-metal-free conditions. Readily accessible or serve as starting materials undergo dearomatization process generate dihydroquinoline dihydropyridine intermediates, which readily react with trifluoracetic anhydride. Subsequent acid-promoted dealkylative rearomatization delivers heteroaryl trifluoromethyl ketones. This tandem is accomplished two-pot, one column process. The trifluoroacetyl group the resulting heteroarenes can be transformed into variety functional groups.

Язык: Английский

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Electrochemical C3‐Thiocyanation of Quinolines

Chinese Journal of Chemistry, Год журнала: 2025, Номер unknown

Опубликована: Май 29, 2025

Comprehensive Summary The site‐selective C–H thiocyanation of quinoline has potential application value but remains undeveloped. We report herein an electrochemical C3‐thiocyanation derivatives under external oxidant‐free conditions. key to success for this reaction is the in situ formation activated silylquinolinium salts. This method exhibits mild conditions, broad substrate scope, and excellent site‐selectivity. practicality protocol further demonstrated by a scale‐up reaction, follow‐up transformations, late‐stage quinoline‐based bioactive molecules.

Язык: Английский

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