The cyclization of 2-amino-3,4,5-trimethoxybenzoic acid (I) with potassium cyanate in water-acetic acid gives 6,7,8-trimethoxy-2,4-(1H,3H)-quinazolinedione (II), which by refluxing with POCl3 is converted into 6,7,8-trimethoxy-2,4-dichloroquinazoline (III). The reaction of (III) with anhydrous NH3 in THF yields 2-chloro-4-amino-6,7,8-trimethoxyquinazoline (IV), which is then condensed with 2-methylallyl-1-piperazinecarboxylate (V) in refluxing isoamyl alcohol (A) to afford 2-methylallyl-4-(4-amino-6,7,8-trimethoxyquinazolin-2-yl)piperazine-1-carboxylate (VI). Finally, the allyl group of (VI) is hydrated by treating with aqueous sulfuric acid, and converted into the hydrochloride by treatment with ethanolic HCl.

The cyclization of 2-amino-3,4,5-trimethoxybenzoic acid (I) with potassium cyanate in water-acetic acid gives 6,7,8-trimethoxy-2,4-(1H,3H)-quinazolinedione (II), which by refluxing with POCl3 is converted into 6,7,8-trimethoxy-2,4-dichloroquinazoline (III). The reaction of (III) with anhydrous NH3 in THF yields 2-chloro-4-amino-6,7,8-trimethoxyquinazoline (IV), which is then condensed with 2-methylallyl-1-piperazinecarboxylate (V) in refluxing isoamyl alcohol (A) to afford 2-methylallyl-4-(4-amino-6,7,8-trimethoxyquinazolin-2-yl)piperazine-1-carboxylate (VI). Finally, the allyl group of (VI) is hydrated by treating with aqueous sulfuric acid, and converted into the hydrochloride by treatment with ethanolic HCl.