Convenient replacement of the hydroxy by an amino group in 4 hydroxycoumarin and 4-hydroxy-6-methyl-2-pyrone under microwave irradiation

Molecules. 2004 Jul 31;9(8):627-31. doi: 10.3390/90800627.


The reaction of 4-hydroxycoumarin (1) with some primary amines 2a-h and morpholine (2i) under microwave irradiation occurred without opening of the lactone ring to give N-substituted 4-aminocoumarins 3a-i in excellent yields. Under the same experimental conditions, 4-hydroxy-6-methyl-2-pyrone (4) reacted with benzylamine (2e) or 2-phenyl- ethylamine (2f) to give the corresponding N,N'-disubstituted 4-amino-6-methyl-2-pyridones 5e,f. The main advantages of this procedure are dramatically shortened reaction times, higher amine utilization and considerably improved yields.

MeSH terms

  • 4-Hydroxycoumarins / chemistry*
  • Hydroxyl Radical / chemistry*
  • Microwaves*
  • Pyrones / chemistry*


  • 4-Hydroxycoumarins
  • Pyrones
  • Hydroxyl Radical
  • 4-hydroxy-6-methyl-2-pyrone