Patent ID: 7820692

Claim:
A compound of general formula (I) or its pharmaceutically acceptable salt: wherein R 1 is each R 2 independently is H, F, Cl, Br, C 1 -C 4 alkyl, OR 5 , or NR 6 R 7 , or all R 2 s together with the benzene ring form 5,6-methylenedioxy, 6,7-methylenedioxy, or 7,8-methylenedioxy; R 3 and R 4 each independently is H, F, Cl, Br, trifluoromethyl, C 1 -C 4 alkyl, OR 5 , or NR 8 R 9 , or all R 2 s together with the benzene ring form 4,5-methylenedioxy, 5,6-methylenedioxy, or 6,7-methylenedioxy; R 5 is H, C 1 -C 4 alkyl, or allyl; R 6 and R 7 each independently is H or C 1 -C 4 alkyl; and R 8 and R 9 each independently is H, C 1 -C 4 alkyl, or allyl.