Rings fluorinated aryl

Aromatic Ring Fluorination. The formation of an aryl diazonium fluoride salt, followed by decomposition, is a classical reaction (the Schiemaim reaction) for aryl fluoride preparation (21). This method has been adapted to the production-scale manufacture of fluorobenzene [462-06-6]... 

The efficacy of ring fluorination depends on the nature and position of the activating group, Y, m the aromatic ring The relative extent of for N (CH3)3 displacement decreases in the following order for Y p-NOy (71%), p-CN (24%), P-CH3CO (15%), p CHO (<5%) = m NO2 (<5%) This fluorodequaternization technique was subsequently adapted to prepare numerous NC A (no-camer-added) F-labeled aryl fluorides [7J, 74]... 

Although for the parent /3,/3-dimethyl styrene 20, the cation binds approximately in the middle and on top of the phenyl ring, for the P-CF3 substituted styrene 143, binding occurs in between the middle of the aryl ring and the fluorine atoms (Figure 4). For the 0-CF3 substituted styrene 145, however, the binding site changes dramatically, and resides closely to the alkene double bond. 

To date, the most effective approach to this problem has been to functionalize the aryl ring of the triphenylphosphine with fluorinated alkyl groups [37-41] ... 

Recently, a few improved methods of direct 18F-fluorination on electron-rich aromatics have been reported, using nucleophilic substitution [33-36] or electrophilic substitution [37-39], These improved methods are encouraging solutions to the complex problem of 18F-fluorination of electron-rich aryl rings. 

Ring-Fluorinated Pyrazolines Fluorinated olefins undergo 1,3-dipolar cycloaddition reactions with diazomethane to produce fluorinated pyrazolines. In some cases, these are not isolated but are directly converted to fluorinated cyclopropanes by extrusion of nitrogen, either thermally or photochemically. For example, reaction of a series of 2-aryl-3-fluoroacrylates with diazomethane produced intermediate fluorinated pyrazolines that were ponverted to a series of 1-aryl-l-cyclopropane carboxylates by irradiation at 3500 A (Fig. 3.75). The esters in turn were... 

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