Phase transfer catalyzed synthesis of 3-methyl-4<i>h</i>-pyrazolo[3,4-<i>d</i>]isoxazole from 3,5-dimethyl-4-isoxazolyldiazonium tetrafluoroborate
作者:E. Rajanarendar、G. Mohan、P. Ramesh、M. Srinivas
DOI:10.1002/jhet.5570440134
日期:2007.1
Reaction of 3,5-dimethyl-4-isoxazolyl-diazonium tetrafluoroborate (2) with two equivalents of potassium acetate and five mole percent of 18-crown-6 in ethanol-free chloroform produce 3-methyl-4H-pyrazolo[3,4-d]isoxazole (3) in good to excellent yield. Pyrazole (3) was subjected to acylation/aroylation to afford the corresponding 4-N-acetyl/aroyl derivatives by reaction with CH3COCl/ArCOCl in Et3N.