p. 4221 - 4224
(1980)p-toluenesulfonylanhydride
(5R,6S)-6-(1-Hydroxy-ethyl)-3,7-dioxo-1-aza-bicyclo[3.2.0]heptane-2-carboxylic acid 4-nitro-benzyl ester
bis-[2-(phenoxyacetyl-amino)-ethyl]-disulfide
{(3S,4R)-3-(1-Hydroxy-ethyl)-2-oxo-4-[2-(2-phenoxy-acetylamino)-ethylsulfanylcarbonylmethyl]-azetidin-1-yl}-acetic acid 4-nitro-benzyl ester
3-Hydroxy-5-{2-hydroxy-1-[2-(2-phenoxy-acetylamino)-ethylsulfanylcarbonyl]-propyl}-1H-pyrrole-2-carboxylic acid 4-nitro-benzyl ester
(5R,6S)-6-(1-Hydroxy-ethyl)-3-[2-(4-nitro-benzyloxycarbonylamino)-ethylsulfanyl]-7-oxo-1-aza-bicyclo[3.2.0]hept-2-ene-2-carboxylic acid 4-nitro-benzyl ester