Novel approach for the conversion of natural Δ 3 cephalosporin derivatives into corresponding Δ 2 cephalosporin derivatives

magnified image A simple one pot synthetic method for the isomerization of cephem double bond from the natural 3‐position to 2‐cephem positions is affected by silylation. Thus cephalosporin acids are treated with Ntrimethylsilylacetamide (MSA) or N,O ‐bis(trimethylsilyl)acetamide (BSA) and the resulting silyl esters are treated with triethylamine at ambient temperature in the same pot to afford Δ 2 ‐cephalosporins, which are potentially related compounds in cephalosporin antibacterial compounds.