Heterocyclic compounds

A compound represented by the formula (I):

• wherein
• R1 and R2 are each independently a hydrogen atom or a substituent, or R1 and R2 are bonded to each other to form, together with the adjacent nitrogen atom, a non-aromatic nitrogen-containing heterocycle that is unsubstituted or that is substituted with from one to three substituents independently selected from Substituent Group A,
• R3 is a C1-6 alkyl group that is unsubstituted or that is substituted with from one to five substituents independently selected from Substituent Group A,
• X is CR4 or N,
• R4, R5 and R6 are each independently a hydrogen atom, a halogen atom, a C1-6 alkyl group that is unsubstituted or that is substituted with from one to five substituents independently selected from Substituent Group A or a C1-6 alkoxy group that is unsubstituted or that is substituted with from one to five substituents independently selected from Substituent Group A, and
• Ring A is a 6-membered aromatic ring optionally further substituted by 1 to 4 substituents selected from (i) a halogen atom, (ii) a C1-6 alkyl group and (iii) a C1-6 alkoxy group,
• or a salt thereof,
• wherein Substituent Group A is the group consisting of:
• (1) a halogen atom,
• (2) a nitro group,
• (3) a cyano group,
• (4) an oxo group,
• (5) a hydroxy group,
• (6) a C1-6 alkoxy group,
• (7) a C6-14 aryloxy group,
• (8) a C7-16 aralkyloxy group,
• (9) a 5- to 14-membered aromatic heterocyclyloxy group,
• (10) a 3- to 14-membered non-aromatic heterocyclyloxy group,
• (11) a C1-6 alkyl-carbonyloxy group,
• (12) a C6-14 aryl-carbonyloxy group,
• (13) a C1-6 alkoxy-carbonyloxy group,
• (14) a mono- or di-C1-6 alkyl-carbamoyloxy group,
• (15) a C6-14 aryl-carbamoyloxy group,
• (16) a 5- to 14-membered aromatic heterocyclylcarbonyloxy group,
• (17) a 3- to 14-membered non-aromatic heterocyclylcarbonyloxy group,
• (18) an C1-6 alkylsulfonyloxy group,
• (19) a C6-14 arylsulfonyloxy group,
• (20) an C1-6 alkylthio group,
• (21) a 5- to 14-membered aromatic heterocyclic group,
• (22) a 3- to 14-membered non-aromatic heterocyclic group,
• (23) a formyl group,
• (24) a carboxy group,
• (25) an C1-6 alkyl-carbonyl group,
• (26) a C6-14 aryl-carbonyl group,
• (27) a 5- to 14-membered aromatic heterocyclylcarbonyl group,
• (28) a 3- to 14-membered non-aromatic heterocyclylcarbonyl group,
• (29) a C1-6 alkoxy-carbonyl group,
• (30) a C6-14 aryloxy-carbonyl group,
• (31) a C7-16 aralkyloxy-carbonyl group,
• (32) a carbamoyl group,
• (33) a thiocarbamoyl group,
• (34) a mono- or di-C1-6 alkyl-carbamoyl group,
• (35) a C6-14 aryl-carbamoyl group,
• (36) a 5- to 14-membered aromatic heterocyclylcarbamoyl group,
• (37) a 3- to 14-membered non-aromatic heterocyclylcarbamoyl group,
• (38) a C1-6 alkylsulfonyl group,
• (39) a C6-14 arylsulfonyl group,
• (40) a 5- to 14-membered aromatic heterocyclylsulfonyl group,
• (41) a C1-6 alkylsulfinyl group,
• (42) a C6-14 arylsulfinyl group,
• (43) a 5- to 14-membered aromatic heterocyclylsulfinyl group,
• (44) an amino group,
• (45) a mono- or di-C1-6 alkylamino group,
• (46) a mono- or di-C6-14 arylamino group,
• (47) a 5- to 14-membered aromatic heterocyclylamino group,
• (48) a C7-16 aralkylamino group,
• (49) a formylamino group,
• (50) a C1-6 alkyl-carbonylamino group,
• (51) a (C1-6 alkyl)(C1-6 alkyl-carbonyl) amino group,
• (52) a C6-14 aryl-carbonylamino group,
• (53) a C1-6 alkoxy-carbonylamino group,
• (54) a C7-16 aralkyloxy-carbonylamino group,
• (55) a C1-6 alkylsulfonylamino group,
• (56) a C6-14 arylsulfonylamino group,
• (57) a C1-6 alkyl group optionally substituted by 1 to 3 halogen atoms,
• (58) a C2-6 alkenyl group,
• (59) a C2-6 alkynyl group,
• (60) a C3-10 cycloalkyl group,
• (61) a C3-10 cycloalkenyl group, and
• (62) a C6-14 aryl group.