A broadened scope for the use of hydrazones as neutral nucleophiles in the presence of H-bonding organocatalysts

Abstract

Using thioureas as H-bonding organocatalysts, nitroalkenes can be activated for the conjugate addition of hydrazones as neutral nucleophiles. Formaldehyde derivatives react at the azomethine carbon as expected, whereas hydrazones from enolizable aldehydes behave as ene-hydrazines and react at the α-carbon instead. Ionic liquids were found to decrease the reaction times considerably compared to commonly used solvents, whereas alternative activation by Lewis acids resulted in decomposition of reactants.