Patent ID: 7368101

Claim:
Process for the preparation of (S)-N,N′-bis[2-hydroxy-1-(hydroxymethyl)ethyl]-5-[(2-hydroxy-1-oxopropyl)amino]-2,4,6-triiodo-1,3-benzenedicarboxamide of formula (I) starting from the compound of formula (II) said process comprising: a) reacting the compound of formula (II) with a suitable protecting agent, to give a compound of formula (III) wherein —R is a group of formula A or B wherein R 1 is a hydrogen atom, a C 1 ÷C 4 straight or branched alkyl group or a C 1 ÷C 4 straight or branched alkoxy group, R 2 is hydrogen, a C 1 ÷C 4 straight or branched alkyl group or a C 1 ÷C 4 straight or-branched -alkoxy group and R 3 is a C 1 ÷C 4 straight or branched alkyl group, a trifluoromethyl or a trichloromethyl group; b) acylating the amino group in position 5 of the intermediate compound of formula (III), by reaction with a (S)-2-(acetyloxy)propanoyl chloride to give a compound of formula (IV) wherein R is as defined above; and c) removing all the acyl groups present in the compound of formula (IV) under basic conditions, with prior cleavage of the cyclic protection under acidic conditions when R is a group of formula A; wherein there is no isolation step of the compound of formula (IV) before step c.