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Regiospecific Syntheses of Functionalized Diaryliodonium Tosylates via [Hydroxy(tosyloxy)iodo]arenes Generated in Situ from (Diacetoxyiodo)arenes

Chun, Joong-Hyun, Pike, Victor W.
Journal of organic chemistry 2012 v.77 no.4 pp. 1931-1938
Lewis bases, aromatic hydrocarbons, benzoic acid, chemical reactions, chemical structure, esters, fluorides, image analysis, organic chemistry, positron-emission tomography, regioselectivity, thiophene
Ready access to ¹⁸F-labeled aryl synthons is required for preparing novel radiotracers for molecular imaging with positron emission tomography. Diaryliodonium salts react with cyclotron-produced no-carrier-added [¹⁸F]fluoride ion to produce [¹⁸F]aryl fluorides. We aimed to prepare functionalized diaryliodonium salts to serve as potential precursors for producing useful ¹⁸F-labeled aryl synthons, such as ¹⁸F-labeled halomethylbenzenes, benzaldehydes, and benzoic acid esters. Such salts were designed to have one functionalized aryl ring, one relatively electron-rich ring, such as 4-methoxyphenyl or 2-thienyl, and a nonfluorine containing weakly nucleophilic anion. Generation of a [hydroxy(tosyloxy)iodo]arene from a functionalized (diacetoxyiodo)arene in situ followed by treatment with an electron-rich arene, such as anisole or thiophene, or with a functionalized arylstannane gave expedient regiospecific access to a wide range of functionally diverse diaryliodonium tosylates in moderate to high yields (44–98%). The described methodology broadens the scope for producing new functionalized diaryliodonium salts for diverse applications.