Patent ID: 8846700

Claim:
A compound represented by a formula (I): wherein the A ring represents a pyrazinyl group, which may have one or two substituent groups selected from the group consisting of lower alkyl, lower alkoxy, halogen, hydroxy, and C 3-7 cycloalkyl, wherein the alkyl substituent group may have 1-3 identical or different substituent groups selected from the group consisting of lower alkoxy groups, halogen atoms and hydroxy groups; the B ring represents a 5- or 6-membered heteroaryl group having 1-3 identical or different hetero atoms selected from the group consisting of nitrogen, sulfur and oxygen atoms; R represents a substituent group selected from the group consisting of lower alkyl, lower alkoxy, halogen, hydroxy and lower alkyl having 1-3 identical or different substituent groups selected from the group consisting of: lower alkoxy groups, halogen atoms or hydroxy groups; k represents an integer of from 0 to 3; R 1 denotes a group represented by a formula (II-1), (II-2), (II-3) or II-4): wherein R 11 and R 12 each independently represent hydrogen, lower alkyl or C 3-7 cycloalkyl, or R 11 and R 12 , together with the nitrogen atom to which they are bound, constitute a 4- to 7-membered nitrogen-containing aliphatic ring (which may be substituted with 1-3 identical or different halogen atoms), or any carbon atom of (CH 2 ) m , together with R 11 or R 12 , may constitute a 4- to 7-membered nitrogen-containing aliphatic ring; any carbon atom in (CH 2 ) m may be substituted with a lower alkyl group; the nitrogen atom to which R 11 and R 12 are bound may form N-oxide; and m represents an integer of from 2 to 6, a group represented by a formula (II-2) —O—(CH 2 ) n —R 13 (II-2) wherein: R 13 represents lower alkoxy, hydroxy or carboxyl; n represents an integer of from 1 to 6; upon R 13 being lower alkoxy, the lower alkoxy, together with any carbon atom of (CH 2 ) n , may form a 5- to 7-membered aliphatic rings; and any carbon atom in (CH 2 ) n may be substituted with a lower alkyl group, a group represented by a formula (II-3) wherein R 14 and R 15 are synonymous with the above R 11 and R 12 ; p represents an integer of from 2 to 6; and R 3 represents a hydrogen atom or a lower alkyl group, or a group represented by a formula (II-4) wherein: R 16 and R 17 are synonymous with the above R 11 and R 12 ; q represents an integer of from 2 to 6; and R 4 represents a hydrogen atom or a lower alkyl group, R 2 is a group selected from the group consisting of: lower alkyl, lower alkoxy, halogen, hydroxy, cyano, carboxyl, alkoxycarbonyl, N-alkylcarbamoyl, N,N-dialkylcarbamoyl, lower alkylsulfonyl and lower alkyl having 1-3 identical or different substituents independently selected from lower alkoxy groups, halogen atoms, hydroxy groups, cyano groups, carboxyl groups, alkoxycarbonyl groups, N-alkylcarbamoyl groups, N,N-dialkylcarbamoyl groups or lower alkylsulfonyl groups, and r represents an integer of from 0 to 3, or a pharmaceutically acceptable salt thereof.