Patent ID: 8044206

Claim:
A nitrogen-containing heterocyclic derivative represented by formula (I) below: wherein symbols in formula (I) above have the following significance: R 1 and R 2 represent H—; R 3 and R 4 , which may be the same or different, represent a lower alkyl; R 5 and R 6 represent H—; R 9 represents an optionally substituted acyl, wherein the optionally substituted acyl is an optionally substituted morpholin-4-ylmethylcarbonyl, an optionally substituted 1,4-oxazepan-4-ylmethylcarbonyl, or an optionally substituted piperidin-1-ylmethylcarbonyl, and wherein the substitutent in the optionally substituted acyl is at least one substituent selected from: R 101 R 102 N, wherein R 101 and R 102 represent H; a lower alkyl which may optionally be substituted with OH; and H 2 N—CO—; R 10 , R 11 , R 12 and R 13 represent H—; A represents piperidin-4-yl; n represents 0, or a pharmaceutically acceptable salt thereof.