898780-54-6Relevant academic research and scientific papers
A convenient and practical heterogeneous palladium-catalyzed carbonylative Suzuki coupling of aryl iodides with formic acid as carbon monoxide source
You, Shengyong,Yan, Chenyu,Zhang, Rongli,Cai, Mingzhong
, (2019/01/04)
A practical heterogeneous palladium-catalyzed carbonylative Suzuki coupling of aryl iodides with arylboronic acids under carbon monoxide gas-free conditions has been developed using a bidentate phosphino-functionalized magnetic nanoparticle-immobilized palladium(II) complex as catalyst. Formic acid was utilized as the carbon monoxide source with dicyclohexylcarbodiimide as the activator, and a wide variety of biaryl ketones were generated in moderate to high yields. The new heterogeneous palladium catalyst can be prepared via a simple procedure and can easily be separated from a reaction mixture by simply applying an external magnet and recycled up to 10 times without any loss of activity.
Iridium-Catalyzed Highly Enantioselective Transfer Hydrogenation of Aryl N-Heteroaryl Ketones with N-Oxide as a Removable ortho-Substituent
Liu, Qixing,Wang, Chunqin,Zhou, Haifeng,Wang, Baigui,Lv, Jinliang,Cao, Lu,Fu, Yigang
supporting information, p. 971 - 974 (2018/02/23)
A highly enantioselective transfer hydrogenation of non-ortho-substituted aryl N-heteroaryl ketones, using readily available chiral diamine-derived iridium complex (S,S)-1f as a catalyst and sodium formate as a hydrogen source in a mixture of H2O/i-PrOH (v/v = 1:1) under ambient conditions, is described. The chiral aryl N-heteroaryl methanols were obtained with up to 98.2% ee by introducing an N-oxide as a removable ortho-substituent. In contrast, no more than 15.1% ee was observed in the absence of an N-oxide moiety. Furthermore, the practical utility of this protocol was also demonstrated by gram-scale asymmetric synthesis of bepotastine besilate in 51% total yield and 99.9% ee.
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
, 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.
Efficient Selenium-Catalyzed Selective C(sp3)?H Oxidation of Benzylpyridines with Molecular Oxygen
Jin, Weiwei,Zheng, Poonnapa,Wong, Wing-Tak,Law, Ga-Lai
, 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.).
Copper-catalyzed oxidative amination of sp3 C-h bonds under air: Synthesis of 1,3-diarylated imidazo[1,5-a ]pyridines
Wang, Huiqiao,Xu, Wentao,Wang, Zhiqiang,Yu, Lintao,Xu, Kun
, p. 2431 - 2435 (2015/04/14)
A copper(II)-catalyzed tandem reaction between pyridine ketone and benzylamine was developed by using clean O2 as an oxidant. This transformation proceeded via an efficient condensation-amination-oxidative dehydrogenation process, affording 1,3-diarylated imidazo[1,5-a]pyridines in excellent yields.
Isolation and characterization of a trinuclear cobalt complex containing trigonal-prismatic cobalt in secondary alcohol aerobic oxidation
Karthikeyan,Alamsetti,Sekar
, p. 1665 - 1671 (2014/05/06)
An unusual trinuclear cobalt complex was successfully isolated and characterized in the Co(OAc)2·4H2O-catalyzed aerobic oxidation of pyridine-based secondary alcohols. In this complex, a cobalt ion (the one in the middle, labeled Co2) has a novel trigonal-prismatic structure coordinated with six oxygen atoms from the substrate. The molecular oxygen present in air plays a major role in enabling this transformation to be catalytic. This aerobic catalytic reaction is very selective to pyridine-based secondary alcohols over primary alcohols.
