457-61-4Relevant academic research and scientific papers
Acylation of 2-benzylpyridine N-oxides and subsequent in situ [3,3]-sigamatropic rearrangement reaction
Antilla, Jon C.,Jing, Hua-qing,Li, Hong-liang
supporting information, (2020/09/22)
An effective method for the acylation of 2-benzylpyridine N-oxides and their fast in situ [3,3]-sigmatropic rearrangement was reported. This transformation has a wide substrate scope under mild conditions, giving moderate to excellent yields. The application for the synthesis of chiral phenyl-2-pyridylmethanol products was briefly explored. Furthermore, an interesting example of tandem substitution and in situ [3,3]-sigamatropic rearrangement of 2-benzylpyridine N-oxide with benzenecarboximidoyl chloride was reported.
Ligand-Free Iridium-Catalyzed Dehydrogenative ortho C?H Borylation of Benzyl-2-Pyridines at Room Temperature
Yang, Yuhuan,Gao, Qian,Xu, Senmiao
, p. 858 - 862 (2019/01/04)
A convenient and ligand-free iridium-catalyzed dehydrogenative ortho C?H borylation of benzyl-2-pyridines has been developed. The reaction proceeds smoothly at room temperature using pinacolborane as a borylating reagent in the presence of catalytic amount of [IrOMe(COD)]2. The reaction is compatible with many functional groups, providing a vast array of ortho borylated products in moderate to excellent yields with excellent selectivities. (Figure presented.).
Metal-Free Halogen(I) Catalysts for the Oxidation of Aryl(heteroaryl)methanes to Ketones or Esters: Selectivity Control by Halogen Bonding
Guha, Somraj,Sekar, Govindasamy
supporting information, p. 14171 - 14182 (2018/09/10)
Metal-free halogen(I) catalysts were used for the selective oxidation of aryl(heteroaryl)methanes [C(sp3)?H] to ketones [C(sp2)=O] or esters [C(sp3)?O]. The synthesis of ketones was performed with a catalytic amount of NBS in DMSO solvent. Experimental studies and density functional theory (DFT) calculations supported the formation of halogen bonding (XB) between the heteroarene and N-bromosuccinimide, which enabled imine–enamine tautomerism of the substrates. No additional activator was required for this crucial step. Isotope-labeling and other supporting experiments suggested that a Kornblum-type oxidation with DMSO and aerobic oxygenation with molecular oxygen took place simultaneously. A background XB-assisted electron transfer between the heteroarenes and halogen(I) catalysts was responsible for the formation of heterobenzylic radicals and, thus, the aerobic oxygenation. For selective acyloxylation (ester formation), a catalytic amount of iodine was employed with tert-butyl hydroperoxide in aliphatic carboxylic acid solvent. Several control reactions, spectroscopic studies, and Time-Dependent Density Functional Theory (TD–DFT) calculations established the presence of acetyl hypoiodite as an active halogen(I) species in the acetoxylation process. With the help of a selectivity study, for the first time we report that the strength of the XB interaction and the frontier orbital mixing between the substrates and acyl hypoiodites determined the extent of the background electron-transfer process and, thus, the selectivity of the reaction.
Photocatalyzed ortho-Alkylation of Pyridine N-Oxides through Alkene Cleavage
Zhou, Wang,Miura, Tomoya,Murakami, Masahiro
supporting information, p. 5139 - 5142 (2018/05/30)
A photocatalyzed reaction of pyridine N-oxides with alkenes gives ortho-alkylated pyridines with cleavage of the carbon–carbon double bond. Benzyl and secondary alkyl groups are incorporated at the ortho position of pyridines in one pot.
Nickel-Catalyzed Hydrogenolysis and Conjugate Addition of 2-(Hydroxymethyl)pyridines via Organozinc Intermediates
Hanna, Luke E.,Harris, Michael R.,Domon, Kenji,Jarvo, Elizabeth R.
, p. 6304 - 6307 (2017/12/08)
2-Hydroxymethylpyridines undergo nickel-catalyzed hydrogenolysis upon activation with a chlorophosphate. Reactions employ diethylzinc and are proposed to proceed through secondary benzylzinc reagents. Quenching with deuteromethanol provides straightforward incorporation of a deuterium label in the benzylic position. Intramolecular conjugate additions with α,β-unsaturated esters are also demonstrated and support the intermediacy of a benzylzinc complex.
Direct Triflylation of Benzylic C—H Bonds with Pyridine as a Directing Group
Yang, Jun,Hu, Juanjuan,Huang, Yangen,Xu, Xiuhua,Qing, Fengling
supporting information, p. 867 - 870 (2017/06/27)
The first example of benzylic C—H triflylation was accomplished with pyridine as a directing group. The reaction of various 2-benzylpyridines and (CF3SO2)2O in the presence of NEt3 in CH2Cl2 proceeded smoothly to afford the corresponding benzyl triflones in moderate to high yields.
Efficient Selenium-Catalyzed Selective C(sp3)?H Oxidation of Benzylpyridines with Molecular Oxygen
Jin, Weiwei,Zheng, Poonnapa,Wong, Wing-Tak,Law, Ga-Lai
supporting information, p. 1588 - 1593 (2017/05/05)
An efficient selenium-catalyzed direct oxidation of benzylpyridines in aqueous DMSO has been successfully developed by using molecular oxygen as the oxidant. A variety of benzoylpyridines with broad functional group tolerance were obtained in modest to excellent yields and with exclusive chemoselectivity. (Figure presented.).
Versatile C(sp2)?C(sp3) Ligand Couplings of Sulfoxides for the Enantioselective Synthesis of Diarylalkanes
Dean, William M.,?iau?iulis, Mindaugas,Storr, Thomas E.,Lewis, William,Stockman, Robert A.
supporting information, p. 10013 - 10016 (2016/08/16)
The reaction of chiral (hetero)aryl benzyl sulfoxides with Grignard reagents affords enantiomerically pure diarylalkanes in up to 98 % yield and greater than 99.5 % enantiomeric excess. This ligand coupling reaction is tolerant to multiple substitution patterns and provides access to diverse areas of chemical space in three operationally simple steps from commercially available reagents. This strategy provides orthogonal access to electron-deficient heteroaromatic compounds, which are traditionally synthesized by transition metal catalyzed cross-couplings, and circumvents common issues associated with proto-demetalation and β-hydride elimination.
Synergistic H4NI-AcOH Catalyzed Oxidation of the Csp3-H Bonds of Benzylpyridines with Molecular Oxygen
Ren, Lanhui,Wang, Lianyue,Lv, Ying,Li, Guosong,Gao, Shuang
supporting information, p. 2078 - 2081 (2015/05/13)
The oxidation of benzylpyridines forming benzoylpyridines was achieved based on a synergistic H4NI-AcOH catalyst and molecular oxygen in high yield under solvent-free conditions. This is the first nonmetallic catalytic system for this oxidation transformation using molecular oxygen as the oxidant. The catalytic system has a wide scope of substrates and excellent chemoselectivity, and this procedure can also be scaled up. The study of a preliminary reaction mechanism demonstrated that the oxidation of the Csp3-H bonds of benzylpyridines was promoted by the pyridinium salts formed by AcOH and benzylpyridines. The synergistic effect of H4NI-AcOH was also demonstrated by control experiments. (Figure Presented).
Direct aerobic oxidation of 2-benzylpyridines in a gas-liquid continuous-flow regime using propylene carbonate as a solvent
Pieber, Bartholomaeus,Kappe, C. Oliver
, p. 320 - 324 (2013/03/28)
The use of high-temperature/pressure gas-liquid continuous flow conditions dramatically enhances the iron-catalyzed aerobic oxidation of 2-benzylpyridines to their corresponding ketones. Pressurized air serves as a readily available oxygen source and propylene carbonate as a green solvent in this radically intensified preparation of synthetically valuable 2-aroylpyridines.
