Zambon Group S.p.a.

Bracco International Bv

Laboratorio Chimico Internazionale S.p.a.

Adare Pharmaceuticals S.r.l.

Antonio Nardi

Marco Villa

Maurizio Paiocchi

Luigi Boltri

Flavio Villani

Paolo Magri'

Process for the preparation of 2-amino-1,3-propanediol

A process for the preparation of (S)-N,N'-bis�2-hydroxy-1-(hydroxymethyl)ethyl!-5-(2-acetoxy-propionylamino )-2,4,6-triiodo-isophthalamide, an intermediate useful for the synthesis of iopamidol, by reaction between L-5-(2-acetoxy-propionylamino)-2,4,6-triiiodoisophthaloyl dichloride and 2-amino-1 ,3-propanediol in N-methylpyrrolidone and in the presence of a base, is described.

Process for the preparation of an intermediate useful in the synthesis

A process for the preparation of 5-amino-1,3-dioxanes of formula (I), comprising the catalytic hydrogenation of the new oximes of formula (II) is described.

Process for the preparation of 5-amino-1,3-dioxanes

A process for the preparation of Iopamidol and 5-amino-2,2-dialkyl-1,3-dioxanes of formula ##STR1## wherein R and R.sub.1 are the same or different and represent a straight or branched C.sub.1 and C.sub.2 alkyl group or together with the carbon atom to which they are bonded, form a C.sub.5 -C.sub.6 cycloaliphatic ring; comprising the transformation of a 2,2-dialkyl-1,3-dioxane-5-carboxylic acid ester of formula ##STR2## wherein R.sub.2 represents a straight or branched C.sub.1 -C.sub.2 alkyl group, a phenyl optionally substituted by nitro groups or a benzyl; by treatment with ammonia into the corresponding amides and the subsequent rearrangement of the latter into the compounds of formula I, by treatment with a hypohalogenite. The resultant ketals may be used as is, or be converted to 2-amino-1,3-propanediol, and reacted with 5-amino-2,4,6-triiodo-isophthalic acid dichloride or, alternatively,L-5-(2-acetoxy-propionylamino)-2,4,6-triido-isophthalic acid dichloride, to produce Iopamidol.

Process for the preparation of iopamidol and

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Paderno Dugnano, Italy

Antonio Nardi