An Elegant One Step Synthesis of 5,6-Disubstituted Isoxazolo [4,5-b]Pyridine-N-oxides

An efficient and modified biginelli one‐pot synthesis of new isoxazole substitted 3,4‐dihydropyrimidin‐2(1H)‐ones and thiones catalyzed by VCl3

“…The application of VCl 3 as catalyst in organic synthesis has been investigated extensively [11][12][13][14][15]. In line with the recent surge in activity in use of VCl 3 and as a sequel to our work on isoxazoles [16][17][18][19][20], we now report a simple efficient and modified Biginelli method for the synthesis of isoxazole substituted 3,4-dihydropyrimidin-2(1H)-ones from aryl aldehydes with isoxazolyl ketoamide and urea/thiourea.…”

Phase transfer catalyzed synthesis of 3‐methyl‐4h‐pyrazolo[3,4‐d]isoxazole from 3,5‐dimethyl‐4‐isoxazolyldiazonium tetrafluoroborate

“…However, this synthesis required the isolation of an explosive diazonium chloride and the use of expensive and hygroscopic tetramethylammonium acetate. In view of this and as a sequel to our work on isoxazoles [6][7][8][9][10] we wish to report a facile phase transfer catalyzed synthesis of pyrazolo [3,4-d]isoxazole from nonexplosive diazonium tetrafluoroborates and inexpensive potassium acetate [11].…”

Phase Transfer Catalyzed Synthesis of 3‐Methyl‐4H‐pyrazolo[3,4‐d]isoxazole from 3,5‐Dimethyl‐4‐isoxazolyldiazonium Tetrafluoroborate.

“…However, this synthesis required the isolation of an explosive diazonium chloride and the use of expensive and hygroscopic tetramethylammonium acetate. In view of this and as a sequel to our work on isoxazoles [6][7][8][9][10] we wish to report a facile phase transfer catalyzed synthesis of pyrazolo [3,4-d]isoxazole from nonexplosive diazonium tetrafluoroborates and inexpensive potassium acetate [11].…”