ZrOCl2.8H2O/SiO2: An efficient and recyclable catalyst for the preparation of coumarin derivatives by Pechmann condensation reaction

Facile iron(III) chloride hexahydrate catalyzed synthesis of coumarins

“…[15][16][17][18][19] The Pechmann reaction 20 is known as one of the most valuable methods for the synthesis of coumarins since it proceeds from simple starting materials, a phenol and a -keto ester, together with an acid catalyst. Various protocols have been developed by using different catalysts including sulfuric acid, 20 trifluoroacetic acid, 21 phosphorus pentaoxide, 22 aluminium chloride, [23][24] indium(III) chloride, 25 titanium(IV) chloride, 26 silica gel supported zirconyl chloride octahydrate, 27 samarium(III) nitrate hexahydrate, 28 bismuth(III) nitrate pentahydrate, 29 ionic liquids 30 and many more. [31][32][33] However, the development of practical, efficient and environmentally benign synthetic protocols for the synthesis of coumarins is greatly desirable.…”

A Novel One‐pot Protocol for Silica Sodium Carbonate‐Catalyzed Synthesis of Pyrano[2,3‐h]coumarins

“…Subsequently, in order to optimize the reaction conditions, the three-component reaction of ethyl cyanoacetate, benzaldehyde, and 4-methyl-5,7-dihydroxycoumarin was selected as a model reaction. The reaction worked efficiently in refluxing MeOH, which afforded the corresponding product 4a in 60% yield ( [15][16][17]. The model reaction without the addition of any catalyst resulted in no product (Table 1, entries [18][19][20].…”

Structural and Catalytic Properties of Sulphated Zirconia doped by Zn Oxide

“…As reported, not only the activated group but also its position in phenol ring has an effective role on the coumarin yield due to resonance and its effect on activation of aromatic ring [13,38]. As well, the catalytic activity depends on the phenolic substrates activity; it is also depend on the structure of the catalyst used.…”

“…Chemically, coumarins can be synthesized by various methods such as the Pechmann reaction, Knoevenagel condensation, Claisen rearrangement, Perkin, Witting, Reformatsky and catalytic cyclization reactions [36,37]. However, acid catalyzed Pechmann reaction is a simple and commonly used method for synthesizing coumarins from activated phenols, mostly m-substituted phenols containing electron donating substituent at m-position and β-keto-esters or an unsaturated carboxylic acids [11,13,38].…”