Abstract
The electrochemical oxidation of potassium trifluoromethanesulfinate
(CF3 SO2 K) in the presence of electron-rich
aromatics and alkenes provides the corresponding trifluoromethylated products.
Key words
trifluoromethylation - potassium trifluoromethanesulfinate - electrolysis - fluorinated compounds - trifluoromethylated
alkanes and alkenes - trifluoromethylated aromatics
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Trifluoromethanesulfinate salts
can be prepared by several routes. From CF3 Br and a source
of radical anion of SO2 :
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10 A representative preparative-scale
electrolysis for the synthesis of 5 /6 is described as follows: A solution of CF3 SO2 K 1 (0.38g, 2.2 mmol) and NEt4 ClO4 (2.87g,
12.5 mmol) in anhyd DMF (50 mL) containing 2 (1.53g,
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under positive nitrogen atmosphere, until the starting material
was almost consumed (as checked by cyclic voltammetry, 2 F/mol).
A circular platinum gauze (5 cm × 5 cm) was used as the
anode which was separated from the cathodic solution (DMF-0.25
M NEt4 ClO4 with platinum as cathode) with
a glass frit of porosity 4. The yellowish solution was hydrolyzed
with brine (150 mL), and extracted with Et2 O (3 × 100
mL). The combined organic solutions were washed with brine (3 × 100
mL), H2 O (3 × 100 mL) and dried over MgSO4 .
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analyzed by 19 F NMR with a known concentration
of PhOCF3 (δF -58.3 ppm/CFCl3 )
as internal standard. 19
F NMR (CDCl3 -CFCl3 ):
1,3-dimethoxy-2-trifluoromethyl benzene 5 , δF -54.26
(s, 3 F); 1,3-dimethoxy-4-trifluoromethyl benzene 6 , δF -60.69
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