P. Johnström, S. Stone-Elander
Feb 1, 1994
Citations
0
Influential Citations
5
Citations
Journal
Journal of Labelled Compounds and Radiopharmaceuticals
Abstract
A method for synthesizing 18F-labelled 2-amino-2′-fluorobenzhydrols under nocarrier-added conditions for use as radiolabelled intermediates in the synthesis of[2′-18F]-1,4-benzodiazepine-2-ones is presented. Anilinodichloroborane reagents were formed by the reaction of boron trichloride with 4-chloro-N-methylaniline, 6a, 4-nitro-N-methylaniline, 6b, 4-nitro-N-ethylaniline, 6c, and 4-chloro-N-(2,2,2-trifluoroethyl)aniline, 6d. 2-[18F]Fluorobenzaldehyde, 5, synthesized in 55–70% yields by the nucleophilic aromatic substitution of 2-nitrobenzaldehyde with the Kryptofix/K+ complex of [18F]F−, was subsequently reacted with the anilinodichloroborane coupling reagents with aromatic substitution occurring ortho to the amino group. The resulting 2-amino-2′-[18F]fluorobenzhydrols, 7a - 7d, were produced in conversions of 60–95% with reaction time ⩽ 10 min at room temperature or 60°C, depending on the aniline used. The total synthesis time, including evaporation of the target water, was 60–65 min. The total radiochemical conversions were of the order of 50–65% for 7a - 7c and 35–45% for 7d, decay-corrected and based on [18F]F−.