- Bulky Selenium Ligand Stabilized Trans-Palladium Dichloride Complexes as Catalyst for Silver-Free Decarboxylative Coupling of Coumarin-3-Carboxylic Acids
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This report describes the syntheses of three new trans-palladium dichloride complexes of bulky selenium ligands. These complexes possess a Cl?Pd?Cl rotor spoke attached to a Se?Pd?Se axle. The new ligands and palladium complexes (C1?C3) were characterized with the help of NMR, HRMS, UV-Vis., IR, and elemental analysis. The single-crystal structure of metal complex C2 confirmed a square planar geometry of complex with trans-orientation. The X-ray structure revealed intramolecular secondary interactions (SeCH—Cl) between chlorine of PdCl2 and CH2 proton of selenium ligand. Variable-temperature NMR data shows coalescence of diastereotopic protons, which indicates pyramidal inversion of selenium atom at elevated temperature. The relaxed potential energy scan of C2 suggests a rotational barrier of ~12.5 kcal/mol for rotation of chlorine atom through Cl?Pd?Cl rotor. The complex C3 possesses dual intramolecular secondary interactions (OCH2—Cl and SeCH2—Cl) with stator ligand. Molecular rotor C2 was found to be a most efficient catalyst for the decarboxylative Heck-coupling under mild reaction conditions. The protocol is applicable to a broad range of substrates with large functional group tolerance and low catalyst loading (2.5 mol %). The mechanism of decarboxylative Heck-coupling reaction was investigated through experimental and computational studies. Importantly the reaction works under silver-free conditions which reduces the cost of overall protocol. Further, the catalyst also worked for decarboxylative arylation and decarboxylative Suzuki-Miyaura coupling reactions with good yields of the coupled products.
- Meena, Neha,Kumar, Sunil,Shinde, Vikki N.,Reddy, S. Rajagopala,Himanshi,Bhuvanesh, Nattamai,Kumar, Anil,Joshi, Hemant
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supporting information
(2022/01/11)
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- Zn(II)-Catalyzed One-Pot Synthesis of Coumarins from Ynamides and Salicylaldehydes
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A highly efficient and straightforward synthesis of diversely substituted coumarins from ynamides and salicylaldehydes in the presence of Zn(II) catalyst has been developed. The sulfonamide moiety of ynamides was successfully recycled in this process, serving as an effective traceless directing group for high regioselectivity in the bond-forming event. The advantages of this protocol are good functional group tolerance, broad substrate scope, simple and high-yielding reaction, recovery/reuse of the sulfonamides, low catalyst loading of inexpensive catalyst, and, by these merits, a more cost-effective and greener process.
- Yoo, Huen Ji,Youn, So Won
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p. 3422 - 3426
(2019/05/10)
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- Hydrolysis and substitution effects on the optical properties of coumarin derivatives studied by vibrational spectroscopy and DFT calculation
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A series of coumarin derivatives have been successfully synthesized. All compounds have been characterized by means of IR and Raman vibrational spectroscopic techniques at the solid state level. Optical absorption and photoluminescence measurements were p
- Khemakhem, Sirine,Elleuch, Slim,Ben Azaza, Najla,Ammar, Houcine,Abid, Younes
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- Synthesis and Evaluation of Coumarin-Resveratrol Hybrids as 15-Lipoxygenaze Inhibitors
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A series of coumarin-resveratrol hybrids, 3-arylcoumarin derivatives 3a-u, were synthesized through the intermolecular condensation reaction of various salicylaldehydes and phenylacetic acids in the presence of 1,4-diazabicyclo[2.2.2]octane under solvent-free conditions. All the synthesized compounds were screened for their inhibitory potency against soybean 15-lipoxygenase. Among them, three compounds (3c, 3j, and 3q) showed good enzyme-inhibitory activities. GRAPHICAL ABSTRACT.
- Rahmani-Nezhad, Samira,Khosravani, Leila,Saeedi, Mina,Divsalar, Kouros,Firoozpour, Loghman,Pourshojaei, Yaghoub,Sarrafi, Yaghoub,Nadri, Hamid,Moradi, Alireza,Mahdavi, Mohammad,Shafiee, Abbas,Foroumadi, Alireza
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supporting information
p. 751 - 759
(2015/10/29)
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- Synthesis and in vitro evaluation of 3-(4-nitrophenyl)coumarin derivatives in tumor cell lines
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Coumarins are naturally-occurring compounds that have attracted considerable interest due to their numerous biological activities depending on their pattern of substitution on the coumarin molecule. In this present investigation, we synthesized 3-(4-nitro
- Musa, Musiliyu A.,Latinwo, Lekan M.,Virgile, Clifford,Badisa, Veera L. D.,Gbadebo, Akintunde J.
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- Synthesis of 3-arylcoumarins via Suzuki-cross-coupling reactions of 3-chlorocoumarin
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A convenient and innovative protocol for an efficient synthesis of different substituted 3-arylcoumarins is reported. The developed synthetic route involves a Pd-catalyzed cross-coupling reaction using a catalytic complex Pd-salen. Under these conditions a series of different substituted boronic acids have been successfully coupled to a coumarin halide to afford novel coumarins in good yields.
- Matos, Maria Joao,Vazquez-Rodriguez, Saleta,Borges, Fernanda,Santana, Lourdes,Uriarte, Eugenio
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experimental part
p. 1225 - 1227
(2011/03/22)
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- One-pot greener protocol for the synthesis of substituted coumarins
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An expeditious one-pot procedure for the synthesis of substituted coumarins under microwave irradiation is accounted. The method describes an easy and fast method for the synthesis of substituted acetoxy coumarins which are very good fluorophores for medical as well as industrial applications. It makes use of easily available reagents such as triethylamine and acetic anhydride as catalyst. The method finds good applications for the synthesis of multisubstituted coumarins.
- Ranjith, Choorikkat,Paul, Nidhin,Vijayan
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experimental part
p. 235 - 238
(2011/11/30)
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- New methodology for the synthesis of 3-substituted coumarins via palladium-catalyzed site-selective cross-coupling reactions
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A particularly useful, easy, and concise synthesis of diversified 3-aryl coumarin was achieved using Heck coupling reactions between coumarin and aryliodides. The introduction of the aryl moiety occurred regioselective at the 3-position of the heteroaromatic ring. Georg Thieme Verlag Stuttgart - New YorK.
- Martins, Sérgio,Branco, Paula S.,Delatorre, María C.,Sierra, Miguel A.,Pereira, António
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supporting information; experimental part
p. 2918 - 2922
(2011/02/26)
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- Photophysical investigation of 3-substituted 4-alkyl and/or 7-acetoxy coumarin derivatives-A study of the effect of substituents on fluorescence
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In the present work an array of novel substituted 2H-chromen-2-one (coumarin) derivatives has been subjected to photophysical analysis. Though the influence of the electron-donating groups such as amino, substituted amino, hydroxyl, alkoxy groups, etc. at position 7 of the coumarin ring system has been extensively studied, the luminescent properties of the coumarin moieties with an acetoxy substituent have not been explored. Herein it is attempted to study the variation of fluorescence behavior of substituted coumarin derivatives with change of nature and position of the substituents on the 2H-chromen-2-one skeleton. Effect of a methyl substituent at position 4 which imposes abnormal photophysical behavior to the chromenone unit has also been briefly described.
- Ranjith, Choorikkat,Vijayan,Praveen, Vakayil K.,Kumar, N.S. Saleesh
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experimental part
p. 1610 - 1616
(2010/06/20)
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- Efficient synthesis of 3-substituted coumarins
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The Mukaiyama's esterification protocol, using 2-chloro-1-methylpyridinium iodide-triethylamine reagent, has been successfully exploited to provide rapid access to a variety of 3-substituted coumarins in satisfactory yields.
- Mashraqui, Sabir H.,Vashi, Dhaval,Mistry, Hitesh D.
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p. 3129 - 3134
(2007/10/03)
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- Coumarins: Fast Synthesis by Knoevenagel Condensation under Microwave Irradiation
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Condensation of salicyaldehyde or its derivatives with various derivatives of ethyl acetate in the presence of piperidine leads to the synthesis of coumarins by a solvent free reaction under microwave irradiation.
- Bogdal, Dariusz
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p. 468 - 469
(2007/10/03)
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- Simple and efficient one-pot preparation of 3-substituted coumarins in water
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3-Cyanocoumarin and seven derivatives [4-Me; 6-NO2; 7-OH; 7-OMe; 8-OH; 5,7-OMe; 6,7-(-CH=CH-)-2] and eight coumarins substituted at C-3 (CO2Et; NO2; Ph; p-NO2-C6H4; Ph-SO2; 2-pyridyl; 2-thienyl; 2-benzothiazolyl) were prepared, on multigram scale by a one-pot procedure in water alone, by the Knoevenagel reaction of o-hydroxyaryl aldehydes and o-hydroxyacetophenone with acetonitriles. The yields are high and the procedure does not require organic solvents. The reactions carried out in heterogeneous aqueous phase, sometimes in the presence of a surfactant, always have higher yields than the same reactions executed in homogeneous ethanolic medium.
- Brufola, Gianluca,Fringuelli, Francesco,Piermatti, Oriana,Pizzo, Ferdinando
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p. 1257 - 1266
(2007/10/03)
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