Heterocyclic indole derivatives and mono- or diazaindole derivatives

A compound represented by formula (1):

• wherein Het represents an optionally substituted heterocyclic group selected from the group consisting of oxetane, furan, dihydrofuran, tetrahydrofuran, pyran, dihydropyran, tetrahydropyran, dioxole, thiophene, dihydrothiophene, tetrahydrothiophene, thiopyran, dihydrothiopyran, tetrahydrothiopyran, pyrrole, dihydropyrrole, pyrrolidine, pyridine, dihydropyridine, tetrahydropyridine, piperidine, pyrazole, 2-pyrazoline, pyrazolidine, imidazole, imidazolidine, pyrimidine, pyrazine, oxazoline, piperazine, 1,2,3-trizole, 1,2,4-triazole, tetrazole, isoxazole, 1,3-oxazole, 1,2,3-oxadiazole, 1,2,4-oxadiazole, 1,2,5-oxadiazole, 1,3,4-oxadiazole, 1,2-thiazole, 1,3-thiazole, 1,2,3-thiadiazole, 1,2,4-thiadiazole, 1,2,5-thiadiazole, 1,3,4-thiadiazole, 1,3-dioxolan, oxazolidine and morpholine;
• A1 and A2 each independently represent —CH═;
• A3 represents —CH2— or —SO2—;
• R1 represents a group selected from the following formulae:
• wherein A4 represents —O—, —S—or —NH—;
• R2 represents a straight or branched alkyl group having 1 to 3 carbon atoms;
• N represents 0, 1 or 2, or pharmaceutically acceptable salts or hydrates thereof.