Beilstein Journal of Organic Chemistry (Nov 2024)

Synthesis of tricarbonylated propargylamine and conversion to 2,5-disubstituted oxazole-4-carboxylates

  • Kento Iwai,
  • Akari Hikasa,
  • Kotaro Yoshioka,
  • Shinki Tani,
  • Kazuto Umezu,
  • Nagatoshi Nishiwaki

DOI
https://doi.org/10.3762/bjoc.20.238
Journal volume & issue
Vol. 20, no. 1
pp. 2827 – 2833

Abstract

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The N,O-acetal derived from diethyl mesoxalate (DEMO) undergoes elimination of acetic acid upon treatment with a base, leading to the formation of N-acylimine in situ. Lithium acetylide readily attacks the imino group to afford N,1,1-tricarbonylated propargylamines. When the resulting propargylamine reacts with butyllithium, ring closure occurs between the ethynyl and carbamoyl groups, yielding 2,5-disubstituted oxazole-4-carboxylates. This cyclization also occurs when the propargylamine is heated with ammonium acetate, resulting in double activation.

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