Triflates perfluoroalkyl phenyliodonium

Attempts to prepare a (/ -fiuorovinyl)iodonium salt from l-decynyl(phenyl)iodonium tetrafluoroborate by the procedures employed for / -chloro- and (/ -bromovinyl)iodonium halides have been unsuccessful103. Admixture of the decynyliodonium salt and lithium fluoride in acetic acid ultimately (2 days, rt) leads to l-acetoxy-2-decanone103. (Z )-(/ -Fluoro-jS-perfluoroalkylvinyl)iodonium triflates, on the other hand, can be made by the treatment of (1H, li/-perfluoroalkyl)phenyliodonium triflates with sodium hydride (equation 178)136. Apart from 2-fluoro-l-hexadecenyl(phenyl)iodonium chloride (synthesis not described)104, these are the only reported examples of (/ -fluorovinyl)iodonium salts. 

Treatment of the anion of acetophenone with (perfluoroalkyl)phenyliodonium triflate (102) led to a poor overall yield of alkylated products. Moreover, the normal alkylation product was contaminated with the product of dehydrofluorination. 

From a synthetic point of view, the synthesis of a-(perfluoroalkyl)ketones is preferably performed by the reaction of (perfluoroalkyl)phenyliodonium triflates with silyl enol ethers, which affords high yields of the perfluoroalkylated products (104) under mild conditions. The reaction of p,7 unsaturated silyl enol ethers with (perfluoroalkyl)phenyliodonium triflates led to the Y-perfluoroalkyl-a,p-unsaturated carbonyl derivatives (105) in good to high yields.212... 

The reaction of enol trimethylsilyl ethers of carbonyl compounds with (a,a-dihydroperfluoroalkyl) phenyliodonium triflates required promotion by potassium fluoride to proceed at room temperature to give the P-perfluoroalkyl carbonyl compounds in good yields.225 in the case of the silyl enol ether of an a,p-unsaturated ketone (119), the 6-perfluoroalkyl-o,p-unsaturated carbonyl compound (120) was the only product formed. The reaction is likely to follow a path similar to the one used in the reaction of silyl enol ethers with (perfluoroalkyl)phenyliodonium salts. In a first step, a ic-complex is formed which evolves into the cationic product of a- or y-addition, followed by desilylation to the carbonyl reaction product. 

Alkyl and aryl thiols afforded with perfluoroalkyl iodonium salts in the presence of pyridine the corresponding sulphides in good to excellent yields [25], Several sulphides and sulphoxides upon reaction with trifluoroethyl phenyliodonium triflate were converted into 2,2,2-trifluoroethyl sulphonium salts [26]. 

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