for reaction times from about 12 to 24 hours preferably about 18 hours it should be stressed that the boiling point of trimethylsilyl azide is 95 99 u00b0 c at 760 mm hg and 52 53 u00b0 c at 175 mm hg for which safety limits are much wider than those for hydrazoic acid b p 35 7 u00b0 c at 760 mm hg the ratio of phosphorous pentachloride to compound of formula iv ranges from about 1 00 to about 1 4 molar preferably approx 1 3 molar the amount of trimethylsilyl azide ranges from about 1 2 to about 1 6 preferably approx 1 45 molar with respect to the amount of starting compound of formula iv the process of the invention is preferably carried out without isolating the haloimine of formula v a further object of the invention is a process for the preparation of cilostazol i in which x is as defined above wherein a compound of formula iii is obtained according to steps a and b as described above the reaction of a compound of formula ii with a compound of formula iii can be carried out according to known methods for example as disclosed in u s pat no 4 277 479 or in u s pat no 6 515 128 the process for the preparation of cilostazol according to the present invention is much safer and less expensive than known processes independently on how the reaction of a compound of formula ii with a compound of formula iii is carried out as the use of hydrazoic acid is avoided and the molar yield in compound iii is usually above 90 15 9 g of phosphorous pentachloride and 12 8 g of n 5 chloropentanoyl cyclohexylamine are.