Morpholine → 4-(4-Nitrobenzyl)morpholine

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Reaction Steps

4-Nitrobenzylbromide (E.0) is treated with morpholine and potassium carbonate in acetone to give 4-(4-nitrobenzyl)morpholine (E.1) of Chart E. The nitro group is reduced with platinum on carbon and hydrogen gas to afford the aniline E.2. lodination employing ICI or NIS provides the amine E.3 which is then treated with diethyl ethoxymethylenemalonate to give the enamine E.4. Cyclization with phosphorous pentoxide in methanesulfonic acid affords the quinoline ester E.5. Aminolysis with p-chlorobenzylamine at elevated temperatures gives the arnide E.6. Coupling with an acetylene employing PdCl2(PPh3)2 and copper iodide and subsequent cyclization provides the desired pyrroloquinolones E.7.

Provenance & Evidence