Synthesis of Imidazolidin-2-ones and Imidazol-2-ones via Base-Catalyzed Intramolecular Hydroamidation of Propargylic Ureas under Ambient Conditions

Alessandra Casnati, Antonio Perrone, Paolo P. Mazzeo, Alessia Bacchi, Raffaella Mancuso, Bartolo Gabriele, Raimondo Maggi, Giovanni Maestri, Elena Motti, András Stirling, Nicola Della Ca

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Abstract

The first organo-catalyzed synthesis of imidazolidin-2-ones and imidazol-2-ones via intramolecular hydroamidation of propargylic ureas is reported. The phosphazene base BEMP turned out to be the most active organo-catalyst compared with guanidine and amidine bases. Excellent chemo- and regioselectivities to five-membered cyclic ureas have been achieved under ambient conditions, with a wide substrate scope and exceptionally short reaction times (down to 1 min). A base-mediated isomerization step to an allenamide intermediate is the most feasible reaction pathway to give imidazol-2-ones, as suggested by DFT studies.

Original languageEnglish
Pages (from-to)3477-3490
Number of pages14
JournalJournal of Organic Chemistry
Volume84
Issue number6
DOIs
Publication statusPublished - Mar 15 2019

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ASJC Scopus subject areas

  • Organic Chemistry

Cite this

Casnati, A., Perrone, A., Mazzeo, P. P., Bacchi, A., Mancuso, R., Gabriele, B., Maggi, R., Maestri, G., Motti, E., Stirling, A., & Ca, N. D. (2019). Synthesis of Imidazolidin-2-ones and Imidazol-2-ones via Base-Catalyzed Intramolecular Hydroamidation of Propargylic Ureas under Ambient Conditions. Journal of Organic Chemistry, 84(6), 3477-3490. https://doi.org/10.1021/acs.joc.9b00064