Modular Synthesis of Pyrazolones Using an Alkene Aminocarbonylation Reaction
Kaitlyn Lavergne1, Amanda Bongers1, Lyanne Betit1
1Centre for Catalysis Research and Innovation, Department of Chemistry and Biomolecular Sciences, University of Ottawa, 10 Marie Curie, Ottawa, Ontario K1N 6N5, Canada.
Abstract:
A variety of pyrazolones were synthesized from enol ethers and hydrazones using a reaction sequence involving aminocarbonylation of enol ethers followed by nucleophile-induced aromatization of the azomethine imines intermediates. Using bases to catalyze the in situ formation of imino isocyanates allowed alkene aminocarbonylation to proceed under milder conditions with reactive substrates and enabled aminocarbonylation reactions of sensitive enol ethers. Aromatization of the azomethine imines could be induced by reduction using NaBH4, or by addition of NH2OH to afford the parent (β)N-H products.
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