Stereoselective Synthesis of Unnatural 6α-trans-2-Oxaisocephams and Δ1(6)-2-Oxaisocephems

Article abstract of DOI:10.1055/s-1997-5786

Several 4β-acetyl-3β-ethyl-N-substituted 2-azetidinones have been synthesized by the Staudinger reaction with D-glucosamine as chiral auxiliary. Attempts to perform an intramolecular cyclisation between the C-4 and N-substituents under ionic conditions at low temperature failed, but at room temperature (thermodynamic control) the bicyclic β-lactams 4-(1,2;3,4-di-O-isopropylidene-1,2,3,4-arabino-tetrahydroxybutyl)-7β-ethyl- 1-methylene-6α-2-oxaisocepham and the Δ¹⁽⁶⁾ isomer were obtained.