LH-Tetrazol-5-thiol

The epioxazoline is successively treated with chlorine, sodium iodide, cuprous oxide and boron trifluoride to produce the exomethylene compound (V). Methoxylation using chlorine with a methoxide followed by reaction with 1-methyl-lH-tetrazole-5-thiol and partial de-blocking using phosphorous pentachloride converts exomethylene (V) into the nucleus (VI). Acylation of the nucleus with an appropriately blocked side-chain (VII) followed by final de-blocking using aluminum chloride gives moxalactam acid (VIII). 

Aminocephalosporanic acid is converted to its sodium salt and acylated with lH-tetrazole-l-acetyl chloride. The acetoxy group is then displaced by reaction with 5-methyl-l,3,4-thiadiazole-2-thiol in buffer solution. The product acid is converted to the sodium salt by NaHC03. 

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