Microwave initiated reactions: Pechmann coumarin synthesis, Biginelli reaction, and acylation

• Published in: Tetrahedron letters Vol. 47; no. 14; pp. 2423 - 2425
• Main Authors: Manhas, Maghar S., Ganguly, Subhendu N., Mukherjee, Somdatta, Jain, Amit K., Bose, Ajay K.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 03-04-2006
• Subjects: Coumarins; Energy-efficient reaction; Microwave chemistry; Solvent-free reaction; Coumarins; Microwave chemistry; Energy-efficient reaction; Solvent-free reaction
• ISSN: 0040-4039; 1873-3581
• DOI: 10.1016/j.tetlet.2006.01.147

Coumarins were synthesized by a solvent-free energy-saving procedure.
An energy-efficient protocol has been developed for solvent-free reactions that are mildly exothermic but not spontaneous. The exothermic reaction mixture—on several g-scale—is exposed for about 30
s to low power (about 200
W) microwaves and then the microwave oven is switched off. After this short burst of energy, the exothermic reaction gets initiated and proceeds on its own to completion. A number of coumarins were synthesized by the Pechmann reaction using this strategy.