preparation of 7 phenylacetamido 3 z e propen 1 yl 3 cephem 4 carboxylic acid cyclohexylamine salt xi 4 methoxybenzyl 7 phenylacetamido 3 z e propen 1 yl 3 cephem 4 carboxylate obtained in step ii above 20 g was dissolved in phenol 20 ml and tfa 5 7 g and it was stirred at 30 to 35 u00b0 c for 3 to 4 hrs the mixture was added to cold mixture of water 100 ml and ethylacetate 100 ml ph was adjusted to 8 0 using 2n naoh solution at 20 22 u00b0 c the aq layer was separated and ethylacetate 140 ml was added and the ph was adjusted to 2 0 to 2 3 using 15 w v sulfuric acid the upper ethyl acetate layer was separated and to this water 25 ml and acetone 50 ml were added cyclohexylamine was added in drops and ph adjusted to 5 5 subsequently the resultant precipitate was stirred filtered washed with ethylacetate 20 ml and dried to give the title compound yield dry 8 2 g purity 99 68 z e ratio 93 1 6 9 preparation of 7 amino 3 z e propen 1 yl 3 cephem 4 carboxylic acid v 7 phenylacetamido 3 z e propen 1 yl 3 ceph em 4 carboxylic acid cyclohexylamine salt 100 g prepared according to the process described in step iii was taken in ethyl acetate.