Synthesis, structural characterization and stereocontrolled degradation of 2-azacephams
摘要:
The enantiomerically pure substituted 2-azacephams 5 were synthesized by intramolecular cyclization of sulfinamides 4. Their absolute configurations were confirmed by X-ray crystal structure: determination of (5R,6R)-4-benzyl-2-isopropylidene-5-oxo-5-thia-1,4-diazabicyclo[4.2.0]octane-3,8-dione 5a. Nucleophilic opening of 2-azacephams by methanol occurred rapidly to give sulfinates 8 with excellent regio and stereoselectivity,