Electrophilic Activation of Acetyl-Substituted Heteroaromatic Compounds

The chemistry of acetyl-substituted pyridines, thiazoles, quinoline, isoquinolines, and pyrazine (1−9 and 28) has been studied. These heteroarenes (1−8) condense with benzene in good yields (74−96%) in the Bronsted superacid, CF3SO3H (triflic acid). In these acid-catalyzed hydroxyalkylation reactions, compounds 1−8 are significantly more reactive than acetophenone. It is proposed that compounds 1−8 readily form dicationic electrophiles in triflic acid.