title: An automated radiosynthesis of 2-[11C]thymidine using anhydrous [11C]urea derived from [11C]phosgene.
abstract: 2-[11C]Thymidine has been produced from [11C]methane via [11C]phosgene and [11C]urea. Anhydrous [11C]urea was prepared from [11C]phosgene by reaction with liquid ammonia. This novel approach avoids the problems associated with the synthesis of anhydrous [11C]urea from [11C]cyanide. A fully automated system based on a modular approach and under PLC control has been developed. The system provides 2-[11C]thymidine reliably and reproducibly for clinical PET studies. The radiosynthesis takes 45-50 min from [11C]methane and the average yield was 1.5-3.3 GBq (40-90 mCi). The specific radioactivity was typically in the range 29.6-51.8 GBq mumol-1 (0.8-1.4 Ci mumol-1) at EOS corresponding to 6-12 micrograms of stable thymidine. The radiochemical yield of 2-[11C]thymidine was ca. 14% from [11C]methane.
authors.affiliation: MRC Cyclotron Unit, Imperial College School of Medicine, Hammersmith Hospital, London, UK.
authors.forename: C J
authors.initials: CJ
authors.lastname: Steel
authors.forename: F
authors.initials: F
authors.lastname: Brady
authors.forename: S K
authors.initials: SK
authors.lastname: Luthra
authors.forename: G
authors.initials: G
authors.lastname: Brown
authors.forename: I
authors.initials: I
authors.lastname: Khan
authors.forename: K G
authors.initials: KG
authors.lastname: Poole
authors.forename: A
authors.initials: A
authors.lastname: Sergis
authors.forename: T
authors.initials: T
authors.lastname: Jones
authors.forename: P M
authors.initials: PM
authors.lastname: Price
mesh_terms: D002250:Carbon Radioisotopes / Q000737:chemistry*; D002251:Carbon Tetrachloride / Q000138:chemical synthesis; D002851:Chromatography, High Pressure Liquid; D007553:Isotope Labeling / Q000379:methods; D008697:Methane / Q000138:chemical synthesis; D010705:Phosgene / Q000138:chemical synthesis*; D011786:Quality Control; D011854:Radiochemistry; D019275:Radiopharmaceuticals / Q000138:chemical synthesis*; D013936:Thymidine / Q000138:chemical synthesis*; D014508:Urea / Q000138:chemical synthesis*
chemical_list: D002250:Carbon Radioisotopes; D019275:Radiopharmaceuticals; D010705:Phosgene; D014508:Urea; D002251:Carbon Tetrachloride; D008697:Methane; D013936:Thymidine