Synthesis and metallation of 2-(pyridyl)benzoic acids and ethyl 2-(pyridyl)benzoates: a new route to azafluorenones

The ring deprotonation of 2-(2- and 4-pyridyl)benzoic acids using lithium dialkylamides in THF at rt, and the in situ cyclization afforded 4- and 2-azafluorenones, respectively. 1-Azafluorenone was obtained from ethyl 2-(3-pyridyl)benzoate using a similar protocol.