3717-17-7Relevant articles and documents
Design and synthesis of sinomenine isoxazole derivatives via 1,3-dipolar cycloaddition reaction
Pan, Hongmei,Lu, Tong,Wu, Xuedan,Gu, Chengwen,Tao, Naili,Zhang, Biao,Wang, Ao,Chen, Guangmei,Zhang, Kehua,Cheng, Jie,Jin, Jie
supporting information, p. 2360 - 2364 (2019/11/11)
A novel structure of sinomenine isoxazole derivatives is synthesised from sinomenine hydrochloride and aromatic aldehydes and requires six steps. 19 target compounds have been obtained in good yields. The sinomenine hydrochloride transforms to 4-alkynyl sinomenine, which is a key intermediate product to synthesise the target sinomenine isoxazole compounds, after a neutralisation reaction with ammonia and substitution reaction with 3-chloropropyne. Another key intermediate product is 1,3-dipole, which can be obtained from aromatic aldehyde. After treatment with hydroxylamine hydrochloride and then sodium carbonate solution, aromatic aldehyde is converted to aldehyde oxime, which reacts with N-chlorosuccinimide (NCS) to afford aryl hydroximino chloride. 1,3-Dipole is eventually formed in situ while triethylamine (TEA) in DMF is added dropwise. Then 4-alkynyl sinomenine is added to provide the sinomenine isoxazole derivative via 1,3-dipolar cycloaddition reaction as the key step. All the target compounds are characterised by melting point, 1H NMR, 13C NMR, HRMS and FT-IR spectroscopy.
Unusual Reactivity of 4-Vinyl Isoxazoles in the Copper-Mediated Synthesis of Pyridines, Employing DMSO as a One-Carbon Surrogate
Kumar, Pravin,Kapur, Manmohan
supporting information, p. 5855 - 5860 (2020/07/30)
An efficient protocol for the synthesis of nicotinate derivatives and tetrasubstituted pyridines through a copper-mediated cleavage of isoxazoles has been developed. The highlight of the work is the observation of an unusual reactivity of 4-vinyl isoxazoles under the reaction conditions. DMSO serves as a one-carbon surrogate generating an active methylene group during the reaction to form two C-C bonds. This protocol provides a facile and an expeditious approach for the assembly of densely substituted N-heterocyclic compounds.
Design, synthesis of novel 4,5-dihydroisoxazole-containing benzamide derivatives as highly potent FtsZ inhibitors capable of killing a variety of MDR Staphylococcus aureus
Song, Di,Bi, Fangchao,Zhang, Nan,Qin, Yinhui,Liu, Xingbang,Teng, Yuetai,Ma, Shutao
supporting information, (2020/09/11)
Antibiotic resistance among clinically significant bacterial pathogens, such as methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant S. aureus (VRSA) is becoming a prevalent threat to public health, and new antibacterial agents with novel mechanisms of action hence are in an urgent need. As a part of continuing effort to develop antibacterial agents, we rationally designed and synthesized two series of 4,5-dihydroisoxazol-5-yl and 4,5-dihydroisoxazol-3-yl-containing benzamide derivatives that targeted the bacterial cell division protein FtsZ. Evaluation of their activity against a panel of Gram-positive and -negative pathogens revealed that compound A16 possessing the 4,5-dihydroisoxazol-5-yl group showed outstanding antibacterial activity (MIC, ≤0.125–0.5 μg/mL) against various testing strains, including methicillin-resistant, penicillin-resistant and clinical isolated S. aureus strains. Besides, further mouse infection model revealed that A16 could be effective in vivo and non-toxic to Hela cells. Finally, a detailed discussion of structure-activity relationships was conducted, referring to the docking results. It is worth noting that substituting a 4,5-dihydroisoxazole ring for the isoxazole ring not only broadened the antibacterial spectrum but also resulted in a significant increase in antibacterial activity against S. aureus strains. Taken together, these results suggest a promising chemotype for the development of new FtsZ-targeting bactericidal agents.
Synthesis and in vitro evaluation of neutral aryloximes as reactivators of Electrophorus eel acetylcholinesterase inhibited by NEMP, a VX surrogate
Cavalcante, Samir F. de A.,Kitagawa, Daniel A.S.,Rodrigues, Rafael B.,Bernardo, Leandro B.,da Silva, Thiago N.,dos Santos, Wellington V.,Correa, Ana Beatriz de A.,de Almeida, Joyce S.F.D.,Fran?a, Tanos C.C.,Ku?a, Kamil,Simas, Alessandro B.C.
, (2019/06/24)
Casualties caused by nerve agents, potent acetylcholinesterase inhibitors, have attracted attention from media recently. Poisoning with these chemicals may be fatal if not correctly addressed. Therefore, research on novel antidotes is clearly warranted. Pyridinium oximes are the only clinically available compounds, but poor penetration into the blood-brain barrier hampers efficient enzyme reactivation at the central nervous system. In searching for structural factors that may be explored in SAR studies, we synthesized and evaluated neutral aryloximes as reactivators for acetylcholinesterase inhibited by NEMP, a VX surrogate. Although few tested compounds reached comparable reactivation results with clinical standards, they may be considered as leads for further optimization.
Vilsmeier-Haack reagent mediated synthetic transformations with an immobilized iridium complex photoredox catalyst
Zhi, Peng,Xi, Zi-Wei,Wang, Dan-Yan,Wang, Wei,Liang, Xue-Zheng,Tao, Fei-Fei,Shen, Run-Pu,Shen, Yong-Miao
supporting information, p. 709 - 717 (2019/01/10)
An immobilized iridium complex photocatalyst Ir(ppy)2(PDVB-py) was synthesized by immobilization of the iridium complex onto the nanoporous vinylpyridine-divinylbenzene copolymer (PDVB-py). Its application for the synthesis of amides, nitriles, and anhydrides was reported via reactions under the action of the visible-light-driven in situ generated Vilsmeier-Haack reagent from CBr4 in DMF. The results showed that this heterogeneous photocatalyst has extremely high activity and excellent stability to be recycled five times.
Catalyst control in positional-selective C-H alkenylation of isoxazoles and a ruthenium-mediated assembly of trisubstituted pyrroles
Kumar, Pravin,Kapur, Manmohan
supporting information, p. 2134 - 2138 (2019/03/26)
High levels of catalyst control are demonstrated in determining the positional selectivity in C-H alkenylation of isoxazoles. A cationic rhodium-mediated, strong-directing group promotes C(sp2)-H activation at the proximal aryl ring whereas, the palladium-mediated electrophilic metallation leads to the C(sp2)-H activation at the distal position of the directing group. Synthetic elaboration of this C-H alkenylation product via ruthenium and copper co-catalysis leads to an efficient method for the assembly of densely substituted pyrroles.
Facile one-pot preparation of 5-aryltetrazoles and 3-arylisoxazoles from aryl bromides
Kobayashi, Eiji,Togo, Hideo
, p. 4226 - 4235 (2018/07/06)
The successive treatment of aryl bromides with n-BuLi, DMF, hydroxylamine hydrochloride, and finally diphenylphosphoryl azide provided efficiently the corresponding 5-aryltetrazoles in good to moderate yields. Similarly, the successive treatment of aryl bromides with n-BuLi, DMF, hydroxylamine hydrochloride, and finally diethyl acetylenedicarboxylate and Oxone provided efficiently the corresponding diethyl 3-arylisoxazole-4,5-dicarboxylates in good to moderate yields. Aromatic aldoximes are the key intermediates in both reactions, and 5-aryltetrazoles and 3-arylisoxazoles could be obtained from aryl bromides in one pot under transition-metal-free conditions.
7-Oxa-4-thia-1-aza-bicyclo[3.2.1]octane 4,4-Dioxides: Mechanochemical Synthesis by Tandem Michael Addition–1,3-Dipolar Cycloaddition of Aldoximes and Evaluation of Antibacterial Activities
Bhutia, Zigmee T.,Das, Avijit,Biswas, Malabika,Chatterjee, Amrita,Banerjee, Mainak
, p. 506 - 514 (2018/02/09)
A solvent-free, green, and efficient mechanochemical method for the synthesis of a series of bridged bicyclo aza-sulfone derivatives, namely 7-oxa-4-thia-1-aza-bicyclo[3.2.1]octane 4,4-dioxides through tandem Michael addition–1,3-dipolar cycloaddition of aldoximes was developed. Mechanochemical grinding/milling facilitates quick formation of aldoximes from corresponding aldehydes and hydroxylamine, which upon reaction with divinyl sulfone in a mixer mill affords 7-oxa-4-thia-1-aza-bicyclo[3.2.1]octane 4,4-dioxide derivatives in good overall yields. The newly synthesized bicyclo aza-sulfone derivatives 4 were screened for antibacterial activities. Mostly bicyclo aza-sulfones derived from electron-rich aromatic aldehydes inhibit the growth of Mycobacterium smegmatis (mc2155) and those from aliphatic aldehydes the growth of Escherichia coli (DH5α) in moderate to good effect. However, butyraldehyde-derived compound 4r was very effective against both M. smegmatis and E. coli. The key advantages of this mechanochemical method are catalyst- and solvent-free conditions, shorter reaction time, and formation of a new series of 7-oxa-4-thia-1-aza-bicyclo[3.2.1]octane 4,4-dioxide derivatives, which are good antibacterial agents against M. smegmatis and E. coli.
Copper-catalysed synthesis of 3,5-disubstituted isoxazoles enabled by pyridinyl benzimidazol (PBI) as a bidentate N-chelating ligand under mild conditions
Khalifeh, Reza,Shahriarpour, Fatemeh,Sharghi, Hashem,Aberi, Mahdi
, p. 813 - 821 (2018/03/01)
In this paper, we introduced pyridinyl benzimidazol (PBI) as an easy-to-handle and bidentate N-chelating ligand that promote clean synthesis of 3,5-disubstituted isoxazoles in the presence of copper acetate as catalyst. This catalytic approach initiates with the hydroxyamination of aldehydes followed by chlorination and then generation of nitrile oxide which subsequently undergoes click-type [3?+?2]-dipolar cycloaddition with alkynes to give isoxazoles. This method provides an alternative green process to construct isoxazole derivatives.
Novel design of recyclable copper(II) complex supported on magnetic nanoparticles as active catalyst for Beckmann rearrangement in poly(ethylene glycol)
Keyhaniyan, Mahdi,Shiri, Ali,Eshghi, Hossein,Khojastehnezhad, Amir
, (2018/05/23)
Copper complex-functionalized magnetic core–shell nanoparticles (Fe3O4@SiO2-Lig-Cu) were prepared and characterized using various techniques. The activity of the new catalyst was tested for the Beckmann rearrangement. The reaction conditions allow for the conversion of a wide variety of aldoximes, including aromatic and heterocyclic ones, to amides in good to excellent yields. High efficiency, mild reaction conditions, easy work-up, use of poly(ethylene glycol) as a green medium and simple purification of products are important advantages of this system. Moreover, the eco-friendly heterogeneous nanocatalyst could be easily recovered from the reaction mixture using an external magnet and reused several times.
