6295-35-8Relevant academic research and scientific papers
Coumarins by Direct Annulation: β-Borylacrylates as Ambiphilic C3-Synthons
Wienhold, Max,Molloy, John J.,Daniliuc, Constantin G.,Gilmour, Ryan
supporting information, p. 685 - 689 (2020/11/30)
Modular β-borylacrylates have been validated as programmable, ambiphilic C3-synthons in the cascade annulation of 2-halo-phenol derivatives to generate structurally and electronically diverse coumarins. Key to this [3+3] disconnection is the BPin unit which serves a dual purpose as both a traceless linker for C(sp2)–C(sp2) coupling, and as a chromophore extension to enable inversion of the alkene geometry via selective energy transfer catalysis. Mild isomerisation is a pre-condition to access 3-substituted coumarins and provides a handle for divergence. The method is showcased in the synthesis of representative natural products that contain this venerable chemotype. Facile entry into π-expanded estrone derivatives modified at the A-ring is disclosed to demonstrate the potential of the method in bioassay development or in drug repurposing.
Gold(I)-Catalyzed Intramolecular Hydroarylation of Phenol-Derived Propiolates and Certain Related Ethers as a Route to Selectively Functionalized Coumarins and 2 H-Chromenes
Cervi, Aymeric,Vo, Yen,Chai, Christina L. L.,Banwell, Martin G.,Lan, Ping,Willis, Anthony C.
, p. 178 - 198 (2020/12/22)
Methods are reported for the efficient assembly of a series of phenol-derived propiolates, including the parent system 56, and their Au(I)-catalyzed cyclization (intramolecular hydroarylation) to give the corresponding coumarins (e.g., 1). Simple syntheses of natural products such as ayapin (144) and scoparone (145) have been realized by such means, and the first of these subject to single-crystal X-ray analysis. A related process is described for the conversion of propargyl ethers such as 156 into the isomeric 2H-chromene precocene I (159), a naturally occurring inhibitor of juvenile hormone biosynthesis.
B(C6F5)3-catalyzed synthesis of coumarins via Pechmann condensation under solvent-free conditions
Prajapti, Santosh Kumar,Rao, S. Prakash
, p. 469 - 473 (2021/03/26)
Tris(pentafluorophenyl)borane [B(C6F5)3] catalyzed simple, efficient and environmentally benign protocol has been developed for the Pechmann condensation using variety of phenols and β-ketoesters under solvent-free conditions to afford coumarin derivatives. The present protocol displayed significant advantages such as low catalyst loading, short reaction time, mild reaction conditions, low toxicity, easy work-up, high yields, and compatibility with other functional groups. In addition, it is a convenient, clean, and fast alternative approach for synthesizing variety of coumarin derivatives. Moreover, the applicability of this method towards large-scale synthesis demonstrated its suitability for the industrial application. Graphic abstract: [Figure not available: see fulltext.]
Synthesis of 6- and 7-alkoxy-4-methylcoumarins from corresponding hydroxy coumarins and their conversion into 6- and 7-alkoxy-4-formylcoumarin derivatives
Ngoc Toan, Vu,Dinh Thanh, Nguyen
supporting information, p. 3603 - 3615 (2020/08/21)
Hydroxy derivatives of 4-methyl-2H-chromen-2-one were prepared from hydroquinone and resorcinol through their reaction with ethyl acetoacetate. These hydroxy coumarins were then converted into corresponding alkoxy derivatives by reaction with alkyl halides. The yields of 6- and 7-alkoxy-4-methylcoumarins 3a–i and 4a–i were 55?95%. Oxidation of these compounds by selenium dioxide under conventional and microwave-assisted heating conditions produced corresponding 4-formyl compounds 5b–h and 6b–h with yields of 40?67% and 90?93%, respectively. Several 6- and 7-alkoxy-4-methylcoumarins 3a–i, 4a–i and nearly all 6- and 7-alkoxy-4-formylcoumarins 5b–h, 6b–h are novel compounds.
Catalytic Activity of a Zr MOF Containing POCOP-Pd Pincer Complexes
Kassie, Abebu A.,Wade, Casey R.
, p. 2214 - 2221 (2020/07/06)
A metal-organic framework assembled from POCOP-Pd pincer complex metallolinkers (1-PdBF4, Zr6O4(OH)4(L-PdMeCN)3(BF4)3, L = (2,6-(OPAr2)2C6H3, Ar = p-C6H4CO2-) has been generated via postsynthetic oxidative I-/BF4- ligand exchange with NOBF4. 1-PdBF4 catalyzes a range of organic transformations, including transfer hydrogenation of unsaturated organic substrates, terminal alkyne hydration, and intramolecular hydroarylation of alkynes. The homogeneous analogue, tBu4POCOP-PdBF4, shows poor catalytic activity for transfer hydrogenation and alkyne hydration and decomposes under the catalytic reaction conditions. Solubility limitations and catalyst deactivation pathways observed for the homogeneous pincer complex propound the advantages of using porous solid supports to immobilize organometallic species.
Preparation of a novel, efficient, and recyclable magnetic catalyst, γ-Fe2O3@HAp-Ag nanoparticles, and a solvent- and halogen-free protocol for the synthesis of coumarin derivatives
Abbasi, Zahra,Rezayati, Sobhan,Bagheri, Maryam,Hajinasiri, Rahimeh
, p. 75 - 82 (2017/01/13)
In this protocol, Ag supported on the hydroxyapatite-core–shell magnetic γ-Fe2O3nanoparticles (γ-Fe2O3@HAp-Ag NPs) as a novel, efficient, and magnetically recyclable catalyst is synthesized, and characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and vibrating sample magnetometry (VSM). The use of the catalyst is described in the synthesis of coumarin derivatives by the Pechmann condensation of various phenols with β-ketoesters under solvent- and halogen-free conditions at 80?°C. This novel and inexpensive method offers advantages, such as recyclability simple experimental protocol, short reaction time, minimal work-up procedure, and excellent yields of products, together with desirable, eco-friendly, green aspects by avoiding toxic elements and solvents, and ease of recovery from the reaction mixture using an external magnet.
Acetamide Derivatives of Chromen-2-ones as Potent Cholinesterase Inhibitors
Prasad, Suchita,Kumar, Bipul,Kumar, Shiv,Chand, Karam,Kamble, Shashank S.,Gautam, Hemant K.,Sharma, Sunil K.
, (2017/08/07)
Alzheimer's disease (AD), a neurodegenerative disorder, is a serious medical issue worldwide with drastic social consequences. Inhibition of cholinesterase is one of the rational and effective approaches to retard the symptoms of AD and, hence, consistent efforts are being made to develop efficient anti-cholinesterase agents. In pursuit of this, a series of 19 acetamide derivatives of chromen-2-ones were synthesized and evaluated for their acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory potential. All the synthesized compounds exhibited significant anti-AChE and anti-BChE activity, with IC50 values in the range of 0.24–10.19 μM and 0.64–30.08 μM, respectively, using donepezil hydrochloride as the standard. Out of 19 compounds screened, 3 compounds, viz. 22, 40, and 43, caused 50% inhibition of AChE at 0.24, 0.25, and 0.25 μM, respectively. A kinetic study revealed them to be mixed-type inhibitors, binding with both the CAS and PAS sites of AChE. The above-selected compounds were found to be effective inhibitors of AChE-induced and self-mediated Aβ1–42 aggregation. ADMET predictions demonstrated that these compounds may possess suitable blood–brain barrier (BBB) permeability. Hemolytic assay results revealed that these compounds did not lyse human RBCs up to a thousand times of their IC50 value. MTT assays performed for the shortlisted compounds showed them to be negligibly toxic after 24 h of treatment with the SH-SY5Y neuroblastoma cells. These results provide insights for further optimization of the scaffolds for designing the next generation of compounds as lead cholinesterase inhibitors.
Introduction of a new ionic liquid solid acid based on clay as an efficient, recyclable and thermally stable catalyst for organic transformations
Beigbaghlou, Somayyeh Sarvi,Marjani, Katayoun,Habibi, Azizollah,Atghia, Seyyed Vahid
, p. 20306 - 20316 (2016/03/01)
Ammonium hydrogen sulfate based ionic liquid immobilized on Na+-montmorillonite (AHS@MMT) was prepared via anchoring ammonium hydrogen sulfate propyltriethoxysilane onto sodium montmorillonite by covalent bonds. The synthesized catalyst was ful
Magnetic nanoparticles functionalized ethane sulfonic acid (MNESA): as an efficient catalyst in the synthesis of coumarin derivatives using Pechmann condensation under mild condition
Samadizadeh, Marjaneh,Nouri, Saeed,Kiani Moghadam, Faeze
, p. 6089 - 6103 (2016/06/01)
This paper reports an efficient heterogeneous catalyst based on sulfonic acid functionalization of magnetic nanoparticles. This new catalyst was prepared using the reaction between magnetic nanoparticles and sodium 2-bromoethane-1-sulfonate. Magnetic nanoparticles functionalized ethane sulfonic acid (MNESA) was found as efficient catalyst for the synthesis of coumarin derivatives using Pechmann condensation under mild condition. This reaction was catalyzed by MNESA under solvent-free condition at 90?°C, to give the corresponding products in excellent yields. The catalyst is easily separated from the reaction condition and can be reused for several times with consistence in the activity.
Synthesis and heterogeneous catalytic activity of covalently immobilized hexamine cation as a magnetically-recoverable nanocatalyst
Kangari, Sahar,Yavari, Issa,Maasoumi, Bakhshali
, p. 1771 - 1779 (2015/08/06)
Functionalized magnetic core-shell nanoparticles Fe3O4-SiO2-HMTA are prepared by co-precipitation method and characterized by SEM, TEM, FT-IR, XRD, and VSM. The particles are spherical with an average size of approximately 48 nm. The catalytic activity of these nanoparticles was tested in solvent-free synthesis of coumarin derivatives. The catalyst was readily recycled by the use of an external magnetic field and can be reused four times without significant loss of activity or mass.
