Carbon nucleophilic displacements on kamiya's azetidinone disulfide: Synthesis of c-2 modified penicillins

Novel carbon nucleophilic displacement reactions on Kamiya's azetidinone disulfide $\text{2}$ and the synthesis of the C-2 modified penams $\text{25}$, $\text{26}$ and $\text{27}$ from the intermediates $\text{8}$, $\text{9}$, and $\text{11}$ are described.