185033-27-6Relevant academic research and scientific papers
Fast and high-yield microreactor syntheses of ortho -substituted [ 18F]Fluoroarenes from reactions of [18F]Fluoride ion with diaryliodonium salts
Chun, Joong-Hyun,Lu, Shuiyu,Lee, Yong-Sok,Pike, Victor W.
supporting information; experimental part, p. 3332 - 3338 (2010/08/20)
A microreactor was applied to produce ortho-substituted [ 18F]fluoroarenes from the reactions of cyclotron-produced [ 18F]fluoride ion (t1/2 = 109.7 min) with diaryliodonium salts. The microreactor provided a very convenient means for running sequential reactions rapidly with small amounts of reagents under well-controlled conditions, thereby allowing reaction kinetics to be followed and Arrhenius activation energies (Ea) to be measured. Prepared symmetrical iodonium chlorides (Ar2I+Cl-) rapidly (6H4, 51%) to high (Ar = Ph or 2-MeC6H4, 85%) decay-corrected radiochemical yields (RCYs) of a single radioactive product (Ar18F). Reaction velocity with respect to Ar group was 2-MeOC6H4 6H4. Activation energies were in the range 18-28 kcal/mol. Prepared unsymmetrical salts (e.g., 2-RC6H 4I+2′-R′C6H4X -; X = Cl or OTs) also rapidly gave two products (2-RC 6H418F and 2-R′C6H 418F) in generally high total RCYs (79-93%). Selectivity for product [18F]fluoroarene was controlled by the nature of the ortho substituents. The power of ortho substituents to impart an ortho-effect was in the following order:, 2,6-di-Me > 2,4,6-tri-Me > Br > Me > Et ≈ iPr ? H > OMe. For (2-methyphenyl)(phenyl)iodonium chloride, the time-course of reaction product selectivity was constant and consistent with the operation of the Curtin-Hammett principle. These results will aid in the design of diaryliodonium salt precursors to 18F- labeled tracers for molecular imaging. This article not subject to U.S. Copyright. Published 2010 by the American Chemical Society.
