Substituted 4‐Oxo‐1,2,3,4‐tetrahydroquinoline‐3‐carboxylic Esters by a Tandem Imine Addition‐SNAr Reaction

A tandem imine addition‐S_NAr annulation reaction has been developed as a new approach to the synthesis of 4‐oxo‐1,2,3,4‐tetrahydroquinoline‐3‐carboxylic esters. A series of these structures has been generated by reacting selected imines with tert‐butyl 2‐fluoro‐5‐nitrobenzoylacetate. Structural variations in the final products are accomplished by changing the substituents on the imine and the alkyl group of the ester. The title compounds are isolated as their enols in 55–97% yield without the need for added base or catalysts. The synthesis of the starting materials as well as mechanistic studies and further synthetic conversions of the products are presented.