Facile and highly stereoselective one-pot synthesis of either (E)- or (Z)-nitro alkenes

Aliphatic aldehydes were reacted with nitro alkanes in the presence of catalytic amounts of piperidine over 4 angstrom molecular sieves. Simply by changing reaction conditions (solvent and temperature) it is possible to control the stereochemical outcome of the reactions, obtaining pure (E)- and (Z)-nitro alkenes in high to excellent yields. The role of molecular sieves on the stereochemical control seems crucial in addition to that of piperidine, especially for the synthesis of the Z isomer.