Bismuth(III) nitrate pentahydrate—a mild and inexpensive reagent for synthesis of coumarins under mild conditions

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.…”

Iodine a Simple, Effective and Inexpensive Catalyst for the Synthesis of Substituted Coumarins

“…Among all these von Pechmann reaction seems to be quite simple and straight forward which employs the condensation of acetoacetic ester with substituted phenols in the presence of a variety of reagents. In the past, several acid catalysts have been used in the von Pechmann reaction including strong acids like sulfuric acid [2], trifluoroacetic acid [7], phosphorous pentachloride [9], aluminium trichloride [10], zinc iodide [11], and many others of the same type including expensive metal halides of indium [12] and palladium [13] and recently Bi 2 (NO 3 ) 3 [14]. Moreover, these catalysts have to be used in excess, for example, sulfuric acid in ten to twelve equivalents [2], trifluoroacetic acid in three to four equivalents [7] and phosphorus pentoxide is required in a five-fold excess.…”

Synthesis of highly substituted indoles in presence of solid acid catalysts

“…The method is highly efficient and free from the aforesaid drawbacks. Phosphated zirconia (P-Zr) (21Á23) and bismuth nitrate penta hydrate (BNPH) (24,25) solid acid catalyst for this transformation. A brief account of the work and its main findings as well as the advantages over the extant synthetic routes is discussed in this communication.…”