The morpholino enamine of monoprotected butane-2,3-dione reacts with cyclic and acyclic conjugated nitroalkenes in a Michael-type reaction to yield nitro-substituted α-diketones, after acidic hydrolysis of the mononitroalkylated enamine adducts. Cyclopentanone, hexahydro-1H-pentalen-2-one and octahydro-2H-inden-2-one derivatives are readily obtained by base-catalyzed intramolecular nitroaldol reaction of the acyclic hydrolysis products.