Reassembly and functionalization of N-CF3 pyridinium salts is reported. The cascade is initiated by hydrolytic ring-opening of N-CF3 pyridinium salts, followed by defluorination, intramolecular nucleophilic addition, intermolecular nucleophilic substitution, and...

A catalytic defluorinative ring-opening indolylation of siloxydifluorocyclopropanes was reported. It was found that AgBF 4-catalyzed reaction of siloxydifluorocyclopropanes with indoles could be controlled to deliver α-fluoro-β-indolylpropanones within 1.5 hours at room temperature. Cyclization of these α-fluoroketone derivatives were then carried out in the presence of trifluoroacetic anhydride in toluene at room temperature. Carbazoles were formed efficiently via an intramolecularly nucleophilic addition of the in situ formed enamine intermediate to the keto carbonyl, followed by a sequential hydrolysis and eliminations of trifluoroacetic acid and hydrogen fluoride.

A new bicyclization of 4-cyano-1,2-diketones with amidines is reported for the construction of tetrahydro-5H-imidazo­[4,5-b]­pyridin-5-ones. The tandem reaction is proposed to involve the double condensation–cyclization of diketone with amidine, an α-ketol like rearrangement, the hydrolysis of nitrile followed by intramolecular nucleophilic addition, and the elimination of water. Features of the bicyclization method include high yields, good functional group tolerance, and mild reaction conditions.