A broadened scope for the use of hydrazones as neutral nucleophiles using H-bond organocatalysts
Daniel Pettersen, Raquel P. Herrera, Luca Bernardi, Francesco Fini, Valentina Sgarzani, Rosario Fernández, José M. Lassaletta, Alfredo Ricci. A broadened scope for the use of hydrazones as neutral nucleophiles using H-bond organocatalysts. Synlett. 2006, Vol. , p. 239-2006.
<p>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 a-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.</p>
<p>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 a-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.</p>