- Process for the preparation of iopamidol and the new intermediated therein
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A process for the preparation of (S)-N,N′-bis[2-hydroxy-1-(hydroxymethyl)ethyl]-5-[(2-hydroxy-1-oxo-propyl)amino]-2,4,6-triiodo-1,3-benzendicarboxamide (iopamidol) starling from 5-amino-N,N′-bis[2-hydroxy-1-(hydroxymethyl)ethyl]-2,4,6-triiodo-1,3-benzenedicarboxamide (II) which process comprises 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 R1 is a hydrogen atom, a C1÷C4 straight or branched alkoxy group, R2 is hydrogen, a C1÷C4 straight or branched alkoxy group and R3 ?is a C1÷C4 straight or branched alkyl group, a trifuoromethyl 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 protections of the hydroxy groups in the carboxamido substituents under acidic conditions, when R is a group of formula A carboxamido hydroxy groups under acidic conditions. The invention also refers to the new intermediates of formula (III) and (IV) wherein —R is a group A.
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- PROCESS FOR THE PREPARATION OF IOPAMIDOL
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The present invention discloses a process for the preparation of pure non-ionic contrast agents. The invention also includes a method for purifying the non-ionic contrast agents.
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- Heterocyclic Nonionic X-ray Contrast Agents. 3. The Synthesis of 5--2,4,6-triiodo-1,3-benzenedicarboxamide Derivatives
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The syntheses of 2,4,6-triiodo-1,3-benzenedicarboxamide analogs, 12c, 12e, and 17c, of interest as X-ray diagnostic agents and in which the 5 position is linked to the N atom of a 4-(hydroxymethyl)-oxazolidin-2-one moiety, are described.The heterocycle was built from suitably protected 5-amino-2,4,6-triiodo-1,3-benzenedicarboxylic acid derivatives by a three-step procedure consisting of (1) phosgene treatment to obtain the corresponding isocyanates, (2) phenylmercuric chloride-catalyzed addition of glycidol (10) resulting in glycidil carbamates, and (3) pyridine-catalyzed intramolecular N-alkylation, followed by deprotection, to obtain the oxazolidin-2-ones.The intramolecular N-alkylation reaction was highly regioselective and was not appreciably accompanied by O-alkylation products under the experimental conditions employed.The two carboxamide nitrogen atoms in the intermediates and end products carry either 2,3-dihydroxypropyl or 1,3-dihydroxypropyl residues.These highly congested benzenoid compounds exhibited interesting NMR spectral features due to atropisomerism arising from hindrance to free rotation about the three single bonds that link the aromatic moiety to the N-containing functionalities.
- Pillai, K. M. R.,Diamantidis, G.,Duncan, L.,Ranganathan, R. S.
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p. 1344 - 1350
(2007/10/02)
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