title: Investigation of SN2 [11C]cyanation for base-sensitive substrates: an improved radiosynthesis of L-[5-11C]-glutamine.
abstract: Carbon-11 (β(+) emitter, t1/2 = 20.4 min) radiolabeled L-glutamine is a potentially useful molecular imaging agent that can be utilized with positron emission tomography for both human oncological diagnosis and plant imaging research. Based upon a previously reported [(11)C]cyanide end-capping labeling method, a systematic investigation of nucleophilic cyanation reactions and acidic hydrolysis reaction parameters, including base, metal ion source, phase transfer catalyst, solvent, reaction temperature and reaction time, was conducted. The result was a milder, more reliable, two-step method which provides L-[5-(11)C]-glutamine with a radiochemical yield of 63.8 ± 8.7% (range from 51 to 74%, n = 10) with >90% radiochemical purity and >90 % enantiomeric purity. The total synthesis time was 40-50 min from the end of bombardment. In addition, an Fmoc derivatization method was developed to measure the specific activity of this radiotracer.
authors.affiliation: Brookhaven National Laboratory, Biological, Environmental and Climate Sciences Department, Upton, NY, 11973, USA.
authors.forename: Tassilo
authors.initials: T
authors.lastname: Gleede
authors.forename: Barbara
authors.initials: B
authors.lastname: Riehl
authors.forename: Colleen
authors.initials: C
authors.lastname: Shea
authors.forename: Lena
authors.initials: L
authors.lastname: Kersting
authors.forename: Aylin Sibel
authors.initials: AS
authors.lastname: Cankaya
authors.forename: David
authors.initials: D
authors.lastname: Alexoff
authors.forename: Michael
authors.initials: M
authors.lastname: Schueller
authors.forename: Joanna S
authors.initials: JS
authors.lastname: Fowler
authors.forename: Wenchao
authors.initials: W
authors.lastname: Qu
mesh_terms: D002247:Carbon Isotopes / Q000737:chemistry; D005973:Glutamine / Q000138:chemical synthesis* / Q000737:chemistry; D006801:Humans; D007553:Isotope Labeling / Q000379:methods*; D011854:Radiochemistry / Q000379:methods
chemical_list: D002247:Carbon Isotopes; D005973:Glutamine