A convenient synthesis of coumarin-3-carboxylic acids via Knoevenagel condensation of Meldrum's acid with ortho-hydroxyaryl aldehydes or ketones

ZrOCl2 · 8H2O: An efficient catalyst for rapid one-pot synthesis of 3-carboxycoumarins under ultrasound irradiation in water

“…To increase both the rate of the chemical reaction and the catalyst efficiency, we combined the catalyst and ultrasonic irradiation in this reaction. In this regard, various protic and aprotic solvents, including water, acetonitrile, N,Ndimethylformamide, dichloromethane, ethanol, diethyl [19] d Lit. [37] e Lit.…”

“…Later on, many one-pot methods have been reported involving microwave irradiation of arylaldehydes and active methylene compounds in the presence of piperidine [16] or ammonium chloride as a catalyst [17], grinding a reaction mixture with ammonium acetate and keeping it overnight [18], and using piperidinium acetate in ethanol under reflux conditions [19]. In recent years much effort has been devoted to preparing coumarin derivatives following greener approaches by using ionic liquid [20][21][22] or aqueous media [23][24][25], zeolites [26], clays [27] and cation exchanged resins [28].…”

Meldrum's Acid Catalyzed Reaction of Tetracyanoethylene and Aldehydes in Water: A Novel Approach to Arylidenemalononitrile

“…[30][31][32][33] General Procedure for the Preparation of Arylidenemalononitriles 5a-i A mixture of tetracyanoethylene (0.128 g, 1.0 mmol), aldehydes 2a-i (1 mmol) and Meldrum's acid (0.014 g, 10 mmol%) was successively added to a screw-capped vial containing a magnetic stirring bar in water (20 ml). The mixture was heated at 80°C in a preheated oil bath for 90 min.…”

One-pot synthesis of potential antioxidant agents, 3-carboxylate coumarin derivatives

“…Coumarin-3-carboxylate is one of the important coumarin derivatives, and an important intermediate that could be used in the synthesis of coumarins (Song et al, 2003). Coumarin-3-acyl derivatives were tested in vitro for their distinct human monoamine oxidase A and B (hMAO-A and hMAO-B) inhibitory activity, especially the 3-ethyl ester coumarin ring.…”