Acidic Alumina as a Useful Heterogeneous Catalyst in the Michael Reaction of β-Dicarbonyl Derivatives with Conjugated Nitroalkenes

Addition of a variety of 1,3-dicarbonyl derivatives to conjugated nitroalkenes was efficiently performed under heterogeneous catalysis by acidic alumina in the presence of a minimum amount of solvent (Et 2 O, 0.5 mL/mmol). The procedure allows satisfactory to good yields of a diastereomeric mixture (∼1:1) of polyfunctionalized adducts. Moreover, work-up can be avoided since the reaction mixture can be directly charged into a chromatographic column for immediate purification.