Molecular rearrangement of 5-(a-hydroxy-alkanoylamino)-2,4,6-triiodo-isophthalic acid amides.

: Iomeprol, a new nonionic contrast agent, undergoes in alkaline solution a Smiles-type intramolecular rearrangement to give 5-methylaminocarbonylmethoxy-2,4,6-triiodoisophthalic acid-bis-(2,3-dihydroxypropylamide). The rearranged product was isolated and its structure confirmed by spectra and by synthesis. The reaction is reversible and could be extended to some structurally related compounds.