BENZIMIDAZOLE DERIVATIVE

PROBLEM TO BE SOLVED: To obtain the above derivative having substance P antagonism and antihistaminic activity and especially useful as a medicine for preventing and treating I type allergic diseases. SOLUTION: This benzimidazole derivative represented by formula I (A is a 1-2C alkylene; B is NR , NR CONR , NR NR CONR , etc., R , R and R are independently H or a 1-4C alkyl; D is a 1-2C alkylene, a 2-3C alkyleneoxy, etc.; Ar is phenyl, etc.; Ar is benzyl, diphenylmethyl, etc.; R and R are each H), e.g. 1-(4-fluorobenzyl)-2-(2-methoxybenzylamino) methylbenzimidazole. The derivative of formula I is obtained by reacting a compound represented by formula II (R is H or a 1-4C alkyl) in an amount of 0.8-1.5 times by mol (based on the compound of formula III) with a compound of formula III in a solvent such as benzene in the presence of a base such as potassium carbonate or trimethylamine at -78 deg.C to a boiling point of the reaction solvent.