(6R)-7t-[(R)-5-benzhydryloxycarbonyl-5-(2,2,2-trichloro-ethoxycarbonylamino)-pentanoylamino]-3-carbamoyloxymethyl-7c-methoxy-8-oxo-(6rH)-5-thia-1-aza-bicyclo[4.2.0]oct-2-ene-2-carboxylic acid benzhydryl ester