Coumarins via knoevenagel condensation reaction (KCR) and pechmann condensation reaction

• Main Authors: Wong, Kok Tong, Basar, Norazah
• Format: Article
• Published: Penerbit UTM Press 2012
• Subjects: TK Electrical engineering. Electronics Nuclear engineering
• Online Access: http://eprints.utm.my/id/eprint/46748/

Knoevenagel condensation reaction (KCR) and Pechmann condensation reaction are the simplest and most widely used method to synthesize various substituted coumarins. The compounds such as 3-acetylcoumarin, 3-acetyl-7-(diethylamino)coumarin, and 7-(diethylamino)-3-(1-oxobutyl)coumarin were synthesized by KCR method which involved the condensation of salicylaldehyde or 4-(diethylamino)salicylaldehyde with ethyl acetoacetate, 4-(diethylamino)- salicylaldehyde with ethyl butyrylacetate in the presence of dimethylamine as a catalyst. Meanwhile, 7-hydroxy-4-methylcoumarin, 4-methyl-2H-benzo[h]chromen-2-one, 7-hydroxy-4,8-dimethyl- coumarin, 7-hydroxy-4-propylcoumarin, 4-propyl-2H-benzo[h]chromen-2-one, 7-hydroxy-8-methyl-4-propylcoumarin and 7,8-dihydroxy-4-propylcoumarin were synthesized through Pechmann condensation reaction by condensation of resorcinol, 1-napthol or 2-methylresorcinol with ethyl acetoacetate, and resorcinol, 1-napthol, 2-methylresorcinol or pyrogallol with ethyl butyrylacetate, respectively in the presence of sulphuric acid as a catalyst. All compounds were characterized by spectroscopic techniques using infrared (IR), proton and carbon nuclear magnetic resonance (1H and 13C NMR).