Zeolite as base catalyst: Nitroaldolic condensation

In this work we have studied the activity and selectivity of alkaline Y and X zeolites to promote the nitroaldolic condensation of aromatic aldehydes with nitroalkanes affording nitroalkenes. The reaction is promoted by the intrinsic basicity of the zeolites, which increases with an increase of both the aluminium content in the framework and the radius of the counter cation. Indeed, high yields and selectivities were obtained carrying out the reactions over CsNaX zeolite. The nature of the reactants, in particular, nitroalkanes, affects the yield and shape selectivity effect was observed. (C) 2000 Academic Press.