Stereochemical studies, 881. Saturated heterocycles, 831 1 Parts 87/82: F. Fülöp, G. Stájer, G. Bernáth, P. Sohár, Tetrahedron, in press. Synthesis of stereoisomeric condensed-skeleton 2-imino-substituted 1,3-oxazines

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Abstract

Thiourea (1a-d, 2a-d) and urea (3a-d, 4a-d) derivatives have been prepared from cis- and trans-2-aminomethyl-1-cyclopentanols, and -l-cyclohexanols and their N-methyl derivatives with phenyl isothiocyanate and phenyl isocyanate, respectively. Treatment of 1 and 2 with methyl iodide and then with alkali furnished - with the exception of the cis-N-methyl derivative - 2-phenylimino-1,3-oxazines (5a,c, 6a-d). The remarkable fact that the ring closure of trans-2-amino-methyl-1-cyclopentanols gives 1,3-heterocycles with trans-anellation supports the assumption that the trans-1,2-disubstituted-1,3-difunctional cyclopentanes undergo ring closure when 1,3-heterocycles with a delocalized pπ bond system are formed. With thionyl chloride the cis-urea derivatives 3a-d afforded an elimination product (8), whereas the trans isomers 4 yielded the cis oxazines 5 by inversion. 1H and 13C NMR spectroscopic studies indicated that in 5a-d, the "O-in" conformers are favoured (the methylene group of the hetero ring is equatorial, while the oxygen atom is axial) and all 3-unsubstituted-2-phenylimino-1,3-oxazines exist exclusively in the tautomeric form with an exo CN bond.

Original languageEnglish
Pages (from-to)5981-5988
Number of pages8
JournalTetrahedron
Volume41
Issue number24
DOIs
Publication statusPublished - 1985

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ASJC Scopus subject areas

  • Biochemistry
  • Drug Discovery
  • Organic Chemistry

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