Patent ID: 7754913

Claim:
A process of forming an isotopically labeled compound of Formula (IIIb) comprising reacting a compound having Formula (IIIa) with ozone in a solvent, wherein said solvent is selected from the group consisting of a C 1 -C 6 alcohol, methylene chloride, and chloroform; wherein R 2 is —CH 2 —R 4 ; R 4 is selected from the group consisting of phenyl, naphthyl, benzofuran, isobenzofuran, indole, benzothiophene, benzimidazole, indazole, benzoxazole, benzisoxazole, benzothiazole, pyridine, quinoline, isoquinoline, pyrazine, quinoxaline, pyridazine, cinnoline and the substituted variants thereof; each R and each R 1 are independently selected from the group consisting of hydrogen, deuterium, and a C 1 -C 4 straight chain or branched alkyl; each y C is selected from the group consisting of 12 C; 13 C or 14 C and at least one of said y C is selected from the group consisting of 13 C or 14 C, wherein the isotopically labeled compound of Formula (IIIb) is isotopically enriched.