Convenient replacement of the hydroxy by an amino group in 4 hydroxycoumarin and 4-hydroxy-6-methyl-2-pyrone under microwave irradiation.
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.
Stoyanov
Edmont V
EV
Faculty of Pharmacy, Medical University of Sofia, Dunav 2, BG-1000 Sofia, Bulgaria.
Ivanov
Ivo C
IC
D015110:4-Hydroxycoumarins / Q000737:chemistry*; D017665:Hydroxyl Radical / Q000737:chemistry*; D008872:Microwaves; D011753:Pyrones / Q000737:chemistry*
D015110:4-Hydroxycoumarins; D011753:Pyrones; D017665:Hydroxyl Radical; C525072:4-hydroxy-6-methyl-2-pyrone