626-55-1Relevant articles and documents
Catalyst-Free N-Deoxygenation by Photoexcitation of Hantzsch Ester
Cardinale, Luana,Jacobi Von Wangelin, Axel,Konev, Mikhail O.
supporting information, (2020/02/15)
A mild and operationally simple protocol for the deoxygenation of a variety of heteroaryl N-oxides and nitroarenes has been developed. A mixture of substrate and Hantzsch ester is proposed to result in an electron donor-acceptor complex, which upon blue-light irradiation undergoes photoinduced electron transfer between the two reactants to afford the products. N-oxide deoxygenation is demonstrated with 22 examples of functionally diverse substrates, and the chemoselective reduction of nitroarenes to the corresponding hydroxylamines is also shown.
Photorelease of Pyridines Using a Metal-Free Photoremovable Protecting Group
Dong, Zaizai,Fang, Xiaohong,Kou, Xiaolong,Tan, Weihong,Tang, Xiao-Jun,Wu, Yayun,Zhang, Zhen,Zhao, Rong,Zhou, Wei
supporting information, p. 18386 - 18389 (2020/08/24)
The photorelease of bioactive molecules has emerged as a valuable tool in biochemistry. Nevertheless, many important bioactive molecules, such as pyridine derivatives, cannot benefit from currently available organic photoremovable protecting groups (PPGs). We found that the inefficient photorelease of pyridines is attributed to intramolecular photoinduced electron transfer (PET) from PPGs to pyridinium ions. To alleviate PET, we rationally designed a strategy to drive the excited state of PPG from S1 to T1 with a heavy atom, and synthesized a new PPG by substitution of the H atom at the 3-position of 7-dietheylamino-coumarin-4-methyl (DEACM) with Br or I. This resulted in an improved photolytic efficiency of the pyridinium ion by hundreds-fold in aqueous solution. The PPG can be applied to various pyridine derivatives. The successful photorelease of a microtubule inhibitor, indibulin, in living cells was demonstrated for the potential application of this strategy in biochemical research.
Synthesis method of 3-bromopyridine
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Paragraph 0017-0024, (2020/05/05)
The invention belongs to the field of organic synthesis, and particularly relates to a synthesis method of 3-bromopyridine. The synthesis method comprises the following steps: (1) dropwise adding bromine into pyridine and 80-95% sulfuric acid at 0 DEG C, and reacting at 130-140 DEG C for 7-8 hours; (2) after the reaction is finished, cooling, pouring into ice water, and regulating the pH value to8 by using 6N sodium hydroxide; and (3) extracting with an organic solvent, layering, drying, filtering, concentrating and distilling. The method has the beneficial effects of high yield, mild reaction conditions, simple reaction steps and simple and easily available raw materials, and is suitable for industrial production.
Base-catalyzed aryl halide isomerization enables the 4-selective substitution of 3-bromopyridines
Bandar, Jeffrey S.,Puleo, Thomas R.
, p. 10517 - 10522 (2020/10/18)
The base-catalyzed isomerization of simple aryl halides is presented and utilized to achieve the 4-selective etherification, hydroxylation and amination of 3-bromopyridines. Mechanistic studies support isomerization of 3-bromopyridines to 4-bromopyridines proceedsviapyridyne intermediates and that 4-substitution selectivity is driven by a facile aromatic substitution reaction. Useful features of a tandem aryl halide isomerization/selective interception approach to aromatic functionalization are demonstrated. Example benefits include the use of readily available and stable 3-bromopyridines in place of less available and stable 4-halogenated congeners and the ability to converge mixtures of 3- and 5-bromopyridines to a single 4-substituted product.
Implementing Hydrogen Atom Transfer (HAT) Catalysis for Rapid and Selective Reductive Photoredox Transformations in Continuous Flow
Steiner, Alexander,Williams, Jason D.,Rincón, Juan A,de Frutos, Oscar,Mateos, Carlos,Kappe, C. Oliver
supporting information, p. 5807 - 5811 (2019/08/01)
The reductive transformation of aryl halides and carbonyl compounds is a key step in many photoredox transformations. By combining a highly reducing organic photocatalyst with a thiol hydrogen atom transfer (HAT) catalyst, we showcase rapid and highly selective reactions of these synthetically important starting materials in continuous flow. The fast reduction of aryl iodides, bromides and chlorides has been demonstrated with residence times in some cases below one minute. Selectivity between mono- and di-dehalogenation could also be achieved in some cases. Aryl ketones, aldehydes and imines were shown to undergo facile pinacol couplings, and the coupling of an aryl chloride with a styrene was also successful.
Axial coordination reactions with nitrogenous bases and determination of equilibrium constants for zinc tetraarylporphyrins containing four β, β ′-fused butano and benzo groups in nonaqueous media
Ye, Lina,Fang, Yuanyuan,Ou, Zhongping,Wang, Liping,Xue, Songlin,Lu, Yang,Kadish, Karl M.
, p. 196 - 206 (2019/02/19)
The axial coordination properties of six zinc tetraarylporphyrins with seven different nitrogenous bases were examined in CH2Cl2 for derivatives containing four β,β′-fused butano or benzo groups and the equilibrium constants (logK) determined using spectral titration methods. The examined compounds are represented as butano(YPh)4PorZn and benzo(YPh)4PorZn, where Por is the porphyrin dianion and Y is a CH3, H or Cl substituent on the para-position of each meso-phenyl ring of the macrocycle. The initial four-coordinate butano-And benzoporphyrins will axially bind one nitrogenous base to form five-coordinate derivatives in CH2Cl2 and this leads to a 4-22 nm red-shift of the Soret and Q bands. The logK values range from 1.98 to 4.69 for butano(YPh)4PorZn and from 3.42 to 5.36 for benzo(YPh)4PorZn, with the exact value depending upon the meso and β-substituents of the porphyrin and the conjugate acid dissociation constants (pKa) of the nitrogenous base.
A Practical and Robust Multistep Continuous Process for Manufacturing 5-Bromo-N-(tert-butyl)pyridine-3-sulfonamide
Yu, Miao,Strotman, Neil A.,Savage, Scott A.,Leung, Simon,Ramirez, Antonio
, p. 2088 - 2095 (2019/10/08)
A multistep continuous flow process involving (1) magnesium-halogen exchange, (2) sulfonylation with sulfuryl chloride, and (3) reaction with tert-butylamine was developed for the synthesis of an arylsulfonamide pharmaceutical intermediate in the synthesis of BMS-919373. The process was successfully implemented, including a robust control strategy to manage the levels of several process impurities, to produce 76 kg of 5-bromo-N-(tert-butyl)pyridine-3-sulfonamide (2). As the instability of the reactive intermediates and existence of strong exotherms made a batch process unsuitable for production beyond a 1 kg scale, the alternative continuous process led to a practical and robust manufacturing route to the active pharmaceutical ingredient.
Synthesis method of 3-bromopyridine
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Paragraph 0017-0024, (2019/05/28)
The invention belongs to the field of organic synthesis, and particularly relates to a synthesis method of 3-bromopyridine. The invention includes following steps: (1), dropwise adding bromine into pyridine and sulfuric acid of 80-95% at 0 DEG C, and allowing reaction at 130-140 DEG C for 7-8h; (2), cooling after reaction is finished, pouring into ice water, and using 6N sodium hydroxide to adjustPH to 8; (3), using an organic solvent for extraction, layering, drying, filtering, concentrating, and distilling. The synthesis method has the advantages of being high in yield, mild in reaction condition, simple in reaction step, simple and easy-to-obtain in raw material and suitable for industrial production.
Molybdenum-Catalyzed Deoxygenation of Heteroaromatic N-Oxides and Hydroxides using Pinacol as Reducing Agent
Rubio-Presa, Rubén,Fernández-Rodríguez, Manuel A.,Pedrosa, María R.,Arnáiz, Francisco J.,Sanz, Roberto
supporting information, p. 1752 - 1757 (2017/05/22)
A molybdenum-catalyzed deoxygenation of pyridine N-oxides and N-hydroxybenzotriazoles, as well as other azole N-oxides, has been developed using pinacol as an environmentally friendly oxo-acceptor. The only by-products are acetone and water making the process a convenient alternative to established protocols in terms of waste generation. The reaction is highly chemoselective and a variety of functional groups are tolerated. The processes are usually very clean allowing the isolation of the pure deoxygenated products after a simple extraction in most cases. (Figure presented.).
Synthesis of bromocyclopropylpyridines via the Sandmeyer reaction
Striela, Romualdas,Urbelis, Gintaras,Sūd?ius, Jurgis,Ston?ius, Sigitas,Sadzevi?ien?, Rita,Labanauskas, Linas
supporting information, p. 1681 - 1683 (2017/04/06)
The reactions of 2-amino-5-cyclopropylpyridine with organic nitrites in the presence of copper(II) halides in various organic solvents were investigated. Optimal reaction conditions for the Sandmeyer reaction were developed and successfully applied to the synthesis of useful building blocks, bromo and chlorocyclopropylpyridines. Aminocyclopropylpyridines were synthesized in high yields from the corresponding aminobromopyridines under standard Suzuki coupling conditions.
