Sulfated titania catalyzed water mediated efficient synthesis of dicoumarols—a green approach

Choline Hydroxide: An Efficient and Biocompatible Basic Catalyst for the Synthesis of Biscoumarins Under Mild Conditions

“…Biscoumarins are usually synthesized through the Domino Knoevenagel-Michael reactions of aldehydes with two equivalents of 4-hydroxycoumarin in the presence of catalyst. The present catalyst systems such as molecular iodine [5], SO 3 Hfunctionalized ionic liquids [6], ionic liquids with both Lewis acid and bronsted acid sites [7], Zn(Proline) 2 [8], sodium dodecyl sulfate [9], p-dodecylbenzenesulfonic acid/piperidine [10], sulfated titania [11], heteorpoly acid [12], nano silica chloride [13], propane-1,2,3-triyltris (hydrogen sulfate) [14] and Ce 2 (SO 4 )Á4H 2 O [15], are almost acidic and often suffered from drawbacks like low yield, long reaction time, high reaction temperature, necessity of refluxing in organic solvent and use of expensive, toxic and unreusable catalyst. In the aspect of green chemistry and industrial application, a non-toxic, reusable and efficient catalytic system at reduced temperature for the synthesis of biscoumarins is in great necessary.…”

A Rapid, Efficient and Green Method for Synthesis of 3,3'-Arylmethylene-bis-4-hydroxycoumarins without Use of any Solvent, Catalyst or Solid Surface

“…We feel that this protocol being a good addition to the currently reported methods 24,25 is in fact better than many others referred herein.…”

Synthesis and characterization, electrical and gas sensing properties of N,N′-bis(salicylidene)-1,2-phenylendiamine substituted novel mono and ball-type metallo phthalocyanines

“…The importance of phthalocyanines (Pcs) in various scientific and technological fields ranging from nanotechnology to medicine is increasing rapidly as a result of newly synthesized compounds [1][2][3][4][5][6][7][8][9]. The physical properties of these compounds can be altered by changing the central metal ion, substituents at peripheral or non-peripheral positions and the ligands attached to the central atom [10][11][12][13][14].…”