saturated heterocycles, 133. Nitrilimine and nitrile oxide cycloaddition to cis-condensed 1,3-dihydrooxazines

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cis-5,6-Tetramethylene-4H-1,3-dihydrooxazine (1) and an analogue unsaturated in the carbocyclic ring (2) give adducts at the heterodouble bond with diphenylnitrilimine or benzonitrile oxide, furnishing 1,3-oxazino-1,2,4-triazolines (3 and 4) or oxadiazolines 5 and 6), respectively. The site-selectivity of the cycloaddition differs from that of the earlier studied norbornene-condensed dihydrooxazines, where the nitrile oxide dipole attacks first the CC and not the CN bond. The conformation of the oxazine rings, the annelation of the hetero rings and the configuration at C-3a have been elucidated by 1H and 13C n.m.r. spectroscopy and for 4 by X-ray analysis. The crystallographic data show that the hetero rings are cis-fused, in accordance with the conclusions inferred from the n.m.r. spectra. The lone pair of the pyramidal N(10) atom is eclipsed with the 3a-aryl ring.

Original languageEnglish
Pages (from-to)5461-5466
Number of pages6
Issue number22
Publication statusPublished - 1987


ASJC Scopus subject areas

  • Biochemistry
  • Drug Discovery
  • Organic Chemistry

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