Electrophilic Activation of 1‐Aryl‐3‐bromo‐2,2‐difluoropropan‐1‐ones by Triflic Acid in Reactions with Arenes

The reactions of 1‐aryl‐3‐bromo‐2,2‐difluoropropan‐1‐ones [Ar(CO)CF2CH2Br] with various arenes Ar′H in the superacid TfOH at room temperature for 1–7 h result in the formation of products of hydroarylation of the carbonyl group, 1,1‐diaryl‐3‐bromo‐2,2‐difluoropropan‐1‐ols [ArAr′C(OH)CF2CH2Br], in yields up to 85 %. The reaction with benzene goes deeper and leads to 1‐aryl‐3‐bromo‐2,2‐difluoro‐1,1‐diphenylpropanes [ArCPh2CF2CH2Br] in good yields. Mainly, the bromomethyl group (CH2Br) of starting ketones remains untouched under the superacidic conditions. Cationic intermediates of the reaction have been studied by means of NMR spectroscopy. Plausible reaction mechanism is discussed. The reactions of 1‐aryl‐3‐bromo‐2,2‐difluoropropan‐1‐ones with arenes in the superacid TfOH result mainly in the formation of products of hydroarylation of the carbonyl group, 1,1‐diaryl‐3‐bromo‐2,2‐difluoropropan‐1‐ols, in the yields up to 85 %.