acid followed by neutralization and filtration the third step of the sequence is the resolution of iii to provide the r and s enantiomers iv and v respectively this can be accomplished by a number of methods known to those skilled in the art including diasteriomeric salt formation with an acid such as l tartaric acid conversion to diasteriomeric amides followed by chemical or chromatographic separation and hydrolysis or chiral chromatography the preferred method is by use of a chiralcel of column such as that described in okamoto et al j chromatogr 363 173 1986 and a mixed solvent system consisting of hexane and isopropanol preferably in the ratio of 2 to 1 the fourth and fifth steps of the synthesis are carried out on enantiomer iv or v depending on which enantiomer of the spirofluorenehydantoin is desired proceeding with iv provides the r enantiomer viii while the s enantiomer ix is obtained from v in either case in the fourth step of the synthesis the r or s amino acid ester iv or v respectively is reacted with cyanate sodium or potassium salts are preferred in a suitable organic acid preferably acetic acid at 45 u00b0 c to 1oo u00b0 c for 15 minutes to 1 hour at a temperature of 6020 c a reaction time of 30 minutes should be sufficient the product is conveniently isolated by diluting the reaction mixture with ice water and collecting the product by filtration at least a 1 1 ratio of the cyanate to the amino acid ester is required for high yields a two to three fold excess of cyanate is not detrimental in the fifth and final step of the synthesis a mixture of the r or s.