Promoters Pechmann coumarin synthesis

The Pechmann coumarin synthesis, also known as the Pechmann condensation or Pechmann reaction, is the Lewis or Bronsted acid-promoted condensation of phenols (1) and P-keto (or other 3-oxo aliphatic) esters (2) to produce coiunarins (2//-chromen-2-ones, 3). ... 

The classical Pechmann approach for the synthesis of coumarins via the micro-wave-promoted reaction [68] has been extended to solvent-free system wherein salicy-... 

The Simonis chromone synthesis is the reaction of a phenol la-c with a P-keto ester 2 using an appropriate acid promoter to generate a chromone or benzo-y-pyrone 3 (also called a benzo-l,4-pyrone). While compound 3 is actually a chromenone, for this article, whether the double bond is present or not, the system will be characterized as a chromone. The condensation is related to the Pechmann-Duisberg reaction, which yields coumarins from the condensation of a phenol with a P-keto ester and like its relative, the reaction conditions require the loss of water from the ketone moiety and alcohol from the ester moiety. 

Phenols undergo acid-promoted cyclocondensation with -ketoesters to give coumarins 13 of variable substitution pattern (Von Pechmann synthesis) [30] ... 

---