An intriguing reaction of 4-hydroxycoumarins with 2,3-dichloro-5,6-dicyanobenzoquinone

DABCO‐modified super‐paramagnetic nanoparticles as an efficient and water‐compatible catalyst for the synthesis of pyrano[3,2‐c:5,6‐c']dichromene‐6,8‐dione derivatives under mild reaction conditions

“…The reaction of 4‐hydroxycoumarine with mandelic acid in acidic conditions was also shown to lead to the pyranochromene derivatives . Regarding the importance of pyrano[3,2‐ c :5,6‐ c ']dichromene‐6,8‐dione derivatives in various biological applications, the synthesis of this class of compounds is of high interest …”

Revised Structure by Computational Methods for a Coumarin Isolated from Zanthoxylum Rhoifolium (Rutaceae)

“…First, despite the fact that hydroxy-and methoxycoumarin are important components of many synthetic and natural products, natural coumarins lacking an oxygen functionality on the aromatic ring and having pyrone ring substitutents, so called simple coumarins, are quite rare [6][7]. In fact, few examples of natural, simple coumarins are known [5,[8][9][10][11], but a much larger number of synthetic ones have been prepared [3,[12][13][14][15][16][17][18][19][20]. Secondly, many biologically active coumarins bearing an oxygen functionality at C-4 occur widely among natural products.…”