Addition of magnesium ester and amide enolates, generated using an excess amount of a magnesium amide (from diisopropylamine and ethylmagnesium bromide), to o-isocyanobenzoates affords 4-hydroxy-3-quinolinecarboxylic esters and amides by a tandem Claisen-type condensation/cyclization sequence.

Alkyl(or aryl)lithiums reacted efficiently with o-isocyano-β-methoxystyrene derivatives, prepared in three steps from o-aminophenyl ketones, to afford the corresponding 2,4-disubstituted quinolines in satisfactory yields.

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Treatment of magnesium enolates of 1-methyl-3,4-dihydroquinolin-2(1H)-ones with nitriles, followed by N-acetylation of the resulting vinylogous urea derivatives with acetic anhydride/pyridine and double bond migration with 1,8-diazabicyclo[5.3.0]undec-7-ene, affords 3-[1-(acetylamino)alkyl]-1-methylquinolin-2(1H)-one derivatives in reasonable overall yields.

A magnesium amide-induced sequential conjugate addition/Claisen-type condensation between methyl 2-(methylamino)benzoate and α,β-unsaturated carboxylates has been found to provide convenient access to 4-hydroxy-1,2-dihydroquinoline-3-carboxylate derivatives and 4-oxo-1,2,3,4-tetrahydroquinoline-3-carboxylates.