Synthesis and new rearrangements of 4-isoxazolin-4,5-dicarboxylic acid derivatives

Coskun N., Ozturk A.

TETRAHEDRON, vol.62, no.51, pp.12057-12063, 2006 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 62 Issue: 51
  • Publication Date: 2006
  • Doi Number: 10.1016/j.tet.2006.09.074
  • Journal Name: TETRAHEDRON
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.12057-12063
  • Keywords: dipolar cycloaddition, nitrones, acyclic azomethine ylides, 4-isoxazolines, pyrrole derivative, 1H-pyrrole-3-carboxylic acid methyl ester, rearrangement, RING-OPENING REACTIONS, 1,3-DIPOLAR CYCLOADDITION REACTIONS, IMIDAZOLINE 3-OXIDES, DIASTEREOSELECTIVE ADDITION, ARYL ISOCYANATES, REACTIVITY, REGIO, 1-BETA-METHYLCARBAPENEM, NITRONES
  • Bursa Uludag University Affiliated: Yes

Abstract

Acyclic nitrones react with dimethyl acetylenedicarboxylate (DMAD) to give stable isoxazolines, from which the ones that contain electron-donating aromatic rings at the C3 position (R-1) were shown to undergo unprecedented fragmentation at room temperature, giving the R-1-aldehyde and inseparable product mixtures, probably due to the formation of highly reactive species such as iminocarbenes. Attempts to convert the isoxazolines to the corresponding stable azomethine ylides, by refluxing in toluene, again led to the same product mixtures as above (e.g., the room temperature decomposition). Isoxazolines when reacted with methoxide at room temperature afforded highly function-alised diastereomeric mixtures. Also, isoxazolines, when reacted with propylamine, gave the corresponding amides regioselectively, all of which were more stable than the parent isoxazolines. (c) 2006 Published by Elsevier Ltd.