PURPOSE: To mass-produce via a simple route the subject compound useful as a synthesis intermediate for an angiotensin II antagonist by a novel process comprising cyclizing a specifically obtained amidine with a specified dicarbonyl compound.

CONSTITUTION: First, a nitrile of the formula: R1CN (wherein R1 is an alkyl, an aryl, or the like) (desirably, propionitrile) is reacted with a thiol of the formula: R5SH (wherein R5 is an alkyl, an aralkyl, or the like) (desirably, benzyl mercaptan) in the presence of a hydrogen halide (desirably, HCl) to obtain a thioimidate hydrohalide of formula I (wherein X is a halogen). Next, this compound is reacted with aminoacetonitrile to obtain an amidine of formula II, and this is cyclized with a 1,3-dicarbonyl compound of formula III (wherein R3 is H, a halogen, or the like; and R6 and R7 are each an aryl, an alkyl, or the like) (desirably, acetylacetone or the like) in the presence of a base (desirably, sodium ethoxide or the like) to obtain the objective compound of formula IV (wherein R2 and R4 are each H, hydroxyl, or the like).