Patent ID: 7030109

Claim:
An isotopically labeled compound of formula (X) or a pharmaceutically acceptable salt or enantiomer thereof wherein R 3 is: (1) —H, (2) C 1 –C 4 alkyl, (3) C 0 –C 4 alkyl-φ where -φ is optionally substituted with up to 2 of the following: (a) —F, —Cl, —Br, —I, (b) —OH, (c) —OC 1 –C 4 alkyl, (d) —CF 3 , (e) —C≡N, (f) —NO 2 , where R N is: (1) —H, (2) C 1 –C 4 alkyl, (3) C 0 –C 4 alkyl-φ where -φ is optionally substituted with up to 2 of the following: (a) —F, —Cl, —Br, —I, (b) —O—R N-1 where R N-1 is —H, C 1 –C 4 alkyl, and -φ, (c) —CF 3 , (d) —C≡N, (e) —NO 2 , where R 9 is: (1) —H, (2) —F, —Cl, (3) C 1 –C 4 alkyl, (4) C 1 –C 3 alkoxy, (5) —CF 3 , (6) C 0 –C 4 alkyl–φwhere -φ is optionally substituted with up to 2 of the following: (a) —F, —Cl, —Br, —I, (b) —O—R 9-1 where R 9-1 is —H, C 1 –C 4 alkyl, and -φ, (c) —CF 3 , (d) —C≡N, (e) —NO 2 (7) —OR 9-1 where R 9-1 is as defined above, wherein the compound of formula X has an isotopic label.