title: Nucleophilic Fluorination and Radiofluorination via Aziridinium Intermediates: N-Substituent Influence, Unexpected Regioselectivity, and Differences between Fluorine-19 and Fluorine-18.
abstract: The efficient dehydrofluorination and radiofluorination of N,N-disubstituted-β-aminoalcohols through an anchimeric-assisted mechanism was developed. An investigation into the influence of N-substituents on the ring opening of the aziridinium intermediate indicated differences in the isomeric ratio and the yields of fluorinated products obtained from N,N-disubstituted-phenylalaninol. This influence was substantial for (18)F-radiofluorination, with yields varying from 0 to 71% at room temperature (RT). Although no significant effects were observed in the fluorine-19 chemistry when the reaction was heated to 90 °C, considerable changes appeared during radiofluorination. In the latter case, the radiochemical yields increased, and degradation of the 2-fluoro-propan-1-amine isomer (b) occurred, leading to a regiospecific reaction in the radiolabeling of [(18)F]-fluorodeprenyl. This method involving nucleophilic radiofluorination at RT was successfully applied to the radiolabeling of [(18)F]-2-fluoroethylamines in which the influence of the N-substituent was also observed.
authors.affiliation: CEA, I2BM, LDM-TEP, UMR 6301 ISTCT , F-14074 Caen, France.|Centre National de la Recherche Scientifique, UMR 6301 ISTCT, LDM-TEP , F-14074 Caen, France.|UNICAEN, UMR 6301 ISTCT, LDM-TEP, GIP Cyceron , BP5229, F-14074 Caen, France.
authors.forename: Marie
authors.initials: M
authors.lastname: Médoc
authors.affiliation: CEA, I2BM, LDM-TEP, UMR 6301 ISTCT , F-14074 Caen, France.|Centre National de la Recherche Scientifique, UMR 6301 ISTCT, LDM-TEP , F-14074 Caen, France.|UNICAEN, UMR 6301 ISTCT, LDM-TEP, GIP Cyceron , BP5229, F-14074 Caen, France.
authors.forename: Franck
authors.initials: F
authors.lastname: Sobrio