Metallation of pyridines and quinolines in the presence of a remote carboxylate group. New syntheses of heterocyclic quinones

2-(3- and 2-Pyridylcarbonyl)benzoic acids (2,3), 2-(2-pyridylcarbonyl)thiophene-3-carboxylic acid (6), 2-(3-quinolylcarbonyl)benzoic acid (10), and most of the corresponding esters (compounds 1,7 and 9 ) are readily synthesized and involved in a deprotonation-condensation sequence. Biologically active aza-anthraquinones such as benzog]isoquinoline-5,10-dione (2-azaanthraquinone, 4 ) and benzog]quinoline-5,10-dione (1-azaanthraquinone, 5) are prepared using the strategy. Extension to other heterocyclic quinones such as thieno3,2-g]quinoline-4,9-dione (8) and benzoj]phenanthridine-7,12-dione (11) is also investigated.