Convenient Synthesis of 4-Hydroxy-1,2-dihydroquinoline-3-carboxylate Derivatives and 4-Oxo-1,2,3,4tetrahydroquinoline-3-carboxylates

A magnesium amide-induced sequential conjugate addition/Claisen-type condensation between methyl 2-(methylamino)benzoate and (alpha),(beta)-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.