Organocatalytic Amination of Pyrazolones with Azodicarboxylates: Scope and Limitations

The organocatalytic amination of pyrazol-5-ones with azodicarboxylates (catalyzed by quinine) is reported. This asymmetric process furnishes enantiomerically enriched hydrazine adducts containing quaternary stereocenters in high yields (74-96 %) and enantioselectivities (up to ee 97 %). Theoretical calculations allow us to propose the relations between quinine catalyst and reactants leading to observed stereochemical outcome and trends in the effectivity of the reaction.

Automated summary

This study reports the organocatalytic amination of pyrazol-5-ones with azodicarboxylates catalyzed by quinine, yielding enantiomerically enriched hydrazine adducts with quaternary stereocenters in high yields and enantioselectivities. Theoretical calculations help propose the relationship between the quinine catalyst and reactants, explaining the observed stereochemical outcome and trends in reaction effectiveness.