| 摘要 |
A process for the preparation of Iopamidol and 5-amino-2,2-dialkyl-1,3-dioxanes of formula <IMAGE> (I) wherein R and R1 are the same or different and represent a straight or branched C1 and C2 alkyl group or together with the carbon atom to which they are bonded, form a C5-C6 cycloaliphatic ring; comprising the transformation of a 2,2-dialkyl-1,3-dioxane-5-carboxylic acid ester of formula <IMAGE> (II) wherein R2 represents a straight or branched C1-C2 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.
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