Caesium fluoroxysulphate

Caesium fluoroxysulphate has been reported to add to alkenes (1-hexene, styrene, cyclohexene and others), furnishing vicinal fluorosulphates. The regio- and stereo-selectivity is rather low and may be partially influenced by the solvent some preference for anti-Markovnikov products and for syw-addition has been observed. The slight predominance of cA-products seems to be consistent with a concerted mechanism173. 

Caesium fluoroxysulphate (CSSO4F) [94] is a solid electrophilic fluorinating agent that is very easily prepared [100] (Figure 3.14) but, unfortunately, is very prone to rapid uncontrolled decomposition. However, it has been used for the fluorination of hydrocarbons [101] and aromatics [102-104] (Figure 3.15). 

Stavber, S. Zupan, M. Reactions of caesium fluoroxysulphate with pyridine. Tetrahedron Lett. 1990, 3i(5),775-776. 

Stavber S, Zupan M (1990) Mild fluorination of uracil derivatives by caesium fluoroxysulphate. Tetrahedron 46 3093-3100... 

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