mls of concentrated hydrogen chloride 37 was added to reduce the ph of the reaction mixture to between 4 5 and 5 5 250 mls of dichloromethane was added to the slurry along with 50 mls water the mixture agitated for 15 minutes and the lower organic phase split off this phase was washed with 50 mls water the aqueous layers combined and back washed with 70 mls dichloromethane the product streams were combined and stripped to dryness the material obtained was 5 39 deoxy 5 fluoro n 4 n pentyloxycarbonylcytidine the crude weight of material obtained was 40 45 grams which represents a yield of 113 from the 50 55 grams of starting material of formula ii to purify the 40 45 grams of 5 39 deoxy 5 fluoro n 4 n pentyloxycarbonyl cytidine obtained from example 2 the residue from example 2 was dissolved in 125 mls ethyl acetate with vigorous agitation product precipitation occurred almost immediately when all the crude material had been dissolved the slurry was cooled to 0 u00b0 c and aged for 1 hour the crystals were recovered and washed twice with 20 mls each hexane ethyl acetate 50 50 ice cold mixture and the ultra white product was dried overnight at 40 u00b0 c with 5 mm hg vacuum the yield was 28 7 g equivalent to an overall yield of 80 based on the 24 5 grams.