Tris(hydrogensulfato) boron as a solid heterogeneous catalyst for the rapid synthesis of α,α′-benzylidene bis(4-hydroxycoumarin) derivatives

Recent Advances in the Synthesis of Biscoumarin Derivatives

“…Tris(hydrogensulfato) boron (B(HSO 4 ) 3 ) ( 57 ) as a catalyst was prepared via the reaction of boric acid ( 56 ) and chlorosulfonic acid ( 18 ) at room temperature (Scheme ). B(HSO 4 ) 3 catalyzed the reaction of 4‐hydroxy coumarin and aromatic aldehydes in a hydroalcoholic medium in a notable short reaction time (3–6 min) (Table , entry 38) …”

“…B(HSO 4 ) 3 0.3 mmol 70 C 3 -6 min 81-98 11 52 yield. Moreover, the catalyst was efficient (76%) after six repeated runs.…”

“…B(HSO 4 ) 3 catalyzed the reaction of 4hydroxy coumarin and aromatic aldehydes in a hydroalcoholic medium in a notable short reaction time (3-6 min) ( Table 1, entry 38). 52 The sulfated titania catalyst (58) was prepared via the reaction of titania powder in anatase form and sulfuric acid at room temperature, and, according to 67 This catalyst was employed for the synthesis of biscoumarins in an efficient, high-yield, easy-work-up and green method. Also, the catalyst had good reusability and recyclability of at least for three times with noticeable yield ( Table 1, entry 40).…”

Visible Light‐Induced Synthesis of Biscoumarin Analogs under Catalyst‐Free Conditions

“…Biscoumarins are an important class that often display diverse biological activities such as antitumor , anti‐inflammatory , antioxidant , and cytotoxicity . These compounds are widely used as ligands , reducing and stabilizing agent , dyes , etc.…”

Introduction of W-doped ZnO nanocomposite as a new and efficient nanocatalyst for the synthesis of biscoumarins in water

“…In recent years and because of these important activities, several methods are reported for the synthesis of biscoumarins using a variety of catalysts and reagents [6][7][8][9][10][11][12][13][14]. These methods although useful but most of them suffer from disadvantages such as long reaction times (e.g., in the presence of piperidine [4], the reactions are performed during 3-4 h), unsatisfactory yields (e.g., when HBF 4 is used as the catalyst the products are obtained in 55-70 % yields [9] ), harsh reaction conditions, expensive reagents, hazardous and toxic solvents (e.g., refluxing toluene is used as the solvent in some of these methodologies [13]) or catalysts and tedious workup.…”