119789-09-2Relevant articles and documents
Oxidative-aromatization of Hantzsch ester 1,4-dihydropyridines by KBrO 3/SnCl4-5H2O under mild condition
Zeynizadeh, Behzad,Dilmaghani, Karim Akbari,Roozijoy, Asli
, p. 557 - 562 (2005)
Different kinds of Hantzsch ester 1,4-dihydropyridines were oxidatively aromatized to their corresponding pyridine derivatives by KBrO 3/SnCl4 · 5H2O system in refluxing CH3CN. The products were obtained in high to excellent yields.
β-Cyclodextrin-catalyzed mild aromatization of hantzsch 1,4-dihydropyridines with o-iodoxybenzoic acid in water/acetone
Chen, Jiang-Min,Zeng, Xiao-Mei
, p. 3521 - 3526 (2009)
Hantzsch 1,4-dihydropyridines undergo smooth aromatization oxidized by o-iodoxybenzoic acid (IBX) in water/acetone in the presence of-cyclodextrin (-CD) to afford the corresponding pyridine derivatives in excellent yields. The IBX and-CD can be recycled and reused.
Reactivity of 1,4-dihydropyridines toward alkyl, alkylperoxyl radicals, and ABTS radical cation
Lopez-Alarcon,Navarrete,Camargo,Squella,Nunez-Vergara
, p. 208 - 215 (2003)
A series of C4-substituted 1,4-dihydropyridines (DHP) with either secondary or tertiary nitrogen in the dihydropyridine ring were synthesized. All of these compounds together with some commercial DHP derivatives were tested for potential scavenger effects toward alkyl, alkylperoxyl radicals, and ABTS radical cation in aqueous media at pH 7.4. Kinetic rate constants were assessed either by UV/vis spectroscopy or GC/MS techniques. Tested compounds reacted faster toward alkylperoxyl radicals and ABTS radical cation than alkyl ones. N-Ethyl-substituted DHPs showed the lowest reactivity. Kinetic results were compared with either trolox or nisoldipine. Using deuterium kinetic isotope effect studies, we have proved that the hydrogen of the 1-position of the DHP ring is involved in the proposed mechanism. This fact is mostly noticeable in the case of alkyl radicals. In all cases, the respective pyridine derivative was detected as the main product of the reaction.
One-pot synthesis of 3-hydroxy-2-oxindole-pyridine hybrids via Hantzsch ester formation, oxidative aromatization and sp3 C–H functionalization using FeWO4 nanoparticles as recyclable heterogeneous catalyst
Paplal, Banoth,Nagaraju, Sakkani,Sathish, Kota,Kashinath, Dhurke
, p. 110 - 115 (2017/10/16)
Synthesis of poly-substituted 3-hydroxy-2-oxindole-pyridine hybrids is reported via sp3 C–H bond functionalization as key steps using FeWO4 nanoparticles as reusable heterogeneous catalyst. Formation of Hantzsch ester (DHP) followed by aromatization, and sp3 C–H bond functionalization was achieved using FeWO4 nanoparticles (20 mol%) at 80 °C. Temperature dependent reactivity was observed for mono aldol (at 80 °C) and bis aldol (at 120 °C) products. The catalyst was regenerated and reused up to 6 cycles without losing catalytic activity. The FeWO4 nanoparticles were also used for oxidative aromatization of different DHP derivatives and for the sp3 C–H functionalization of 2-methyl pyridine.
Study of temperature dependent three component dynamic covalent assembly VIa Hantzsch reaction catalyzed by dioxido- and oxidoperoxidomolybdenum(VI) complexes under solvent free conditions
Maurya, Mannar R.,Saini, Neeraj,Avecilla, Fernando
, p. 12993 - 13009 (2016/02/12)
Tridentate ONO donor ligands derived from heterocyclic compound 4-acetyl-3-methyl-1-phenyl-2-pyrazoline-5-one (Hap) and aromatic hydrazides {benzoyl hydrazide (Hbhz), isonicotinoyl hydrazide (Hinh), nicotinoyl hydrazide (Hnah) and furoyl hydrazide (Hfah)} react with [MoVIO2(acac)2] (Hacac = acetylacetone) in equimolar ratio in methanol to give dioxidomolybdenum(vi) complexes, [MoO2(ap-bhz)(MeOH)] 1, [MoO2(ap-inh)(MeOH)] 2, [MoO2(ap-nah)(MeOH)] 3 and [MoO2(ap-fah)(MeOH)] 4. Reaction of these ligands with in situ generated oxidoperoxidomolybdenum(vi) precursor results in the formation of oxidoperoxidomolybdenum(vi) complexes, [MoO(O2)(ap-bhz)(MeOH)] 5, MoO(O2)(ap-inh)(MeOH)] 6, MoO(O2)(ap-nah)(MeOH)] 7 and MoO(O2)(ap-fah)(MeOH)] 8. These complexes have been characterized by elemental analysis, spectroscopic techniques (infrared, UV-vis, 1H and 13C NMR) and thermogravemetric analysis. The structures of complexes [MoVIO2(ap-bhz)(H2O)] 1a (water coordinated), [MoVIO2(ap-bhz)(DMSO)] 1b (DMSO coordinated), [MoVIO2(ap-nah)(DMF)] 3a (DMF coordinated), [MoVIO(O2)(ap-bhz)(MeOH)] 5 (methanol coordinated) and [MoVIO(O2)(Hap-nah)(OMe)]·MeOH 7a (methoxy coordinated) have been confirmed by single crystal X-ray studies. X-ray diffraction study also reveals that tridentate ligands bind to the metal center through enolic oxygen (of pyrazolol), azomethine nitrogen and enolic oxygen (of hydrazide) atoms. In complex 7a, pyridinic nitrogen is protonated. These complexes [dioxidomolybdenum(vi) as well as oxidoperoxidomolybdenum(vi)] have been tested as catalysts for temperature dependent one pot three component (methylacetoacetate, benzaldehyde and ammonium acetate) dynamic covalent assembly, via Hantzsch reaction, using 30% H2O2 as a green oxidant under solvent free conditions. Various parameters such as the amount of catalyst, oxidant and temperature of the reaction mixture have been taken into consideration to optimize the reaction conditions. In the Hantzsch reaction, the temperature and oxidant control the conversion and selectivity of the desired product.
