Y Zinc Chloride Mediated Synthesis of 1,4-Oxazepines from N-Propargylic -Enaminones


Kelgokmen Y. , Çayan Y., Zora M.

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, pp.7167-7178, 2017 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Publication Date: 2017
  • Doi Number: 10.1002/ejoc.201701433
  • Title of Journal : EUROPEAN JOURNAL OF ORGANIC CHEMISTRY
  • Page Numbers: pp.7167-7178
  • Keywords: Heterocycles, Cyclization, Alkynes, Lewis acids, Synthetic methods, HIV-1 REVERSE-TRANSCRIPTASE, POTENT PGE(2) ANTAGONIST, BETA-ENAMINONES, FACILE SYNTHESIS, INTRAMOLECULAR CYCLIZATION, DERIVATIVES, CHEMISTRY, AMOXAPINE, FLUORINE, DIACYLHYDRAZINE

Abstract

An efficient and general method for the synthesis of 1,4-oxazepines is described. When reacted with ZnCl2 in DCM at 40 degrees C or CHCl3 at 61 degrees C, N-propargylic -enaminones undergo 7-exo-dig cyclization to afford 2-methylene-2,3-dihydro-1,4-oxazepines in good to high yields. This cyclization has been found to be general for a diverse range of N-propargylic -enaminones, and proceeds with high efficiency and with broad functional group tolerance. The reactions in refluxing CHCl3 produced 1,4-oxazepines in comparatively short reaction times and with better yields that those obtained in refluxing DCM. This operationally easy method may provide rapid access to a library of functionalized 1,4-oxazepine derivatives of pharmacological interest.