Dipolar cycloadditions of imidazoline 3-oxides with N-arylmaleimides. Synthesis and diethylamine induced ring-opening of exo and endo hexahydro-7-oxa-2,5,6a-triaza-cyclopenta[a]pentalene-1,3-diones

Coskun N., Mert H., Arikan N.

TETRAHEDRON, vol.62, no.7, pp.1351-1359, 2006 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 62 Issue: 7
  • Publication Date: 2006
  • Doi Number: 10.1016/j.tet.2005.11.038
  • Journal Name: TETRAHEDRON
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.1351-1359
  • Keywords: cyclic nitrone, 1,3-dipolar cycloaddition, 3-imidazoline 3-oxides, sec-amine induced ring-opening, 3-imidazoline, 1,3-DIPOLAR CYCLOADDITION, DIASTEREOSELECTIVE ADDITION, ARYL ISOCYANATES, REGIO, REACTIVITY, NITRONE, IMIDES
  • Bursa Uludag University Affiliated: Yes

Abstract

14-Diarylimidazoline 3-oxides react with N-arylmaleimides in benzene to give predominantly the corresponding endo adducts. Chiral imidazoline 3-oxides react diastereospecifically (cis configuration of the tetrahydroimidazo ring) and diastereoselectively to give cis-endo adducts. The effects of substituents on the aromatic ring of the maleimide was investigated. The presence of electron-withdrawing or releasing group,; have minor effect on the total yields but more pronounced is the effect on the ratio of exo and endo diastereomers. The adducts undergo an interesting and unprecedented ring-opening in the presence of secondary amines to give deoxygenated 3-imidazoline 3-oxides instead of the expected double cis elimination products. Tertiary amines did not induce any reaction, (c) 2005 Elsevier Ltd. All rights reserved.