10.1039/a700650k
The research focuses on the enantioselective synthesis of 2-isocephem and 2-isooxacephem antibiotics, which are nuclear analogues of β-lactam antibiotics and have shown potent antibacterial activity. The purpose of the study was to develop a method for synthesizing enantiomerically pure forms of these compounds, addressing the challenge of constructing cis-oriented chiral centers at the azetidinone ring. The researchers used L-aspartic acid as a chiral starting material and successfully synthesized the target compounds through a series of chemical reactions involving azide introduction, four-component condensation, and intramolecular acylation. Key chemicals used in the process included azido lactone, p-nitrobenzyl isocyanide, formaldehyde, 2,2-diethoxyacetaldehyde, and various protecting and deprotecting agents.