3-Amino-5-methylisoxazole → Isoxicam

Participants

Reaction Conditions

Reaction Steps

To an appropriate flask equipped for reflux and/or distillation, 900 ml xylene, 40 grams (.149 moles) methyl 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxylate 1,1-dioxide and 19.94 grams (.203 moles) of 3-amino-5-methylisoxazole are added. The mixture is refluxed for 13-18 hours. At one hour intervals, about 3-4% of the solvent volume is distilled off. Every 4 to 5 hours fresh xylene is added, equal in amount to that distilled during this period. At the end of the heating period, the reaction is cooled to 25° C., filtered and the cake is washed with xylene. After drying, the crude product weighed 43.8 grams (88%). This material could be recrystallized from about 40-50 volumes of dioxane with an 80-85% recovery of acceptable material. An alternate procedure for the purification of crude product is as follows:

Provenance & Evidence