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Synlett 1990; 1990(7): 431-432
DOI: 10.1055/s-1990-21119
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Synthesis of Azetidinones from L-Threonine: Formation of Unusually Stable Bicyclic Hemiketals and cis-Azetidinones

M. Kugelman* , D. Gala, R. S. Jaret, P. L. Nyce, A. T. McPhail
  • *Process Research and Development, Schering Plough Corporation, Bloomfield, NJ 07003, USA
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Publication Date:
08 March 2002 (online)

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L-Threonine-based synthesis of azetidinones/penems leads to the desired trans-azetidinones as well as novel, unusually stable bicyclic hemiketals/cis-azetidinones. The latter compounds are resistant to Baeyer-Villiger oxidation, and hence they can not be used towards penem synthesis. Structures of the bicyclic hemiketal, (1S,2R, 4R,5R)-4-(4-chlorophenyl)-4-hydroxy-6-(4-methoxyphenyl)-2-methyl-3-oxa-6-azabicyclo[3.2.0]heptan-7-one, and the cis-azetidione, (3S, 4R)-3-[(R)-1-(acetoxy)ethyl]-4-(4-chlorobenzoyl)-1-(4-methoxyphenyl)-2-azetidinone, were established by x-ray crystallography.

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