ETHYL-N-(O-ETHYNYL)MALONANILIDE AS A USEFUL BUILDING-BLOCK FOR THE PREPARATION OF 3,4-DISUBSTITUTED-2(1H)-QUINOLONES, 3,4-DISUBSTITUTED-QUINOLINE AND 2,3,4-TRISUBSTITUTED-QUINOLINE

3,4-Disubstituted-2(1H)-quinolones have been prepared through a proced ure based on the palladium-catalysed reaction of the readily available ethyl N-(o-ethynyl))malonanilide with aryl, heteroaryl and vinyl hali des or vinyl triflates followed by the cyclization of the resulting co upling derivatives under basic conditions. It is shown that 3,4-disubs tituted-2(1H)-quinolones are useful synthetic intermediates for the pr eparation of 3,4-disubstituted- and 2,3,4-trisubstituted quinolines.