(5-thioxo-4,5-dihydro-tetrazol-1-ylmethyl)-phosphonic acid 、
(5-thioxo-4,5-dihydro-tetrazol-1-ylmethyl)-phosphonic acid diethyl ester 、 3-acetoxymethyl-7-aminoceph-3-em-4-carboxylic acid 生成 7β-amino-3-(1-phosphono-methyltetrazol-5-ylthiomethyl)-3-cephem-4-carboxylic acid 、 7β-amino-3-(1-diethoxyphosphinylmethyltetrazol-5-ylthiomethyl)-3-cephem-4-carboxylic acid