Process for making 4-methyl-4,5-dihydrotetrazolo 1,5-a! quinazolin-5-one

摘要

In a process for preparing the compound 4-methyl-4,5- dihydrotetrazolo 1,5-a! quinazolin-5-one having the structural formula: ##STR1## which comprises the steps of (i) bringing anthranilic acid into reaction with cyanamide at a temperature in the range of 80° to 100° C.; (ii) bringing the reaction product obtained by the foregoing step (i) into reaction with hydrazine hydrate in the presence of an organic solvent; then (iii) diazotizing the hydrazino compound so formed to yield a tetrazole; and finally (iv) methylating the tetrazole, the improvement which comprises using n-butanol as the organic solvent in step (ii).