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US 8,138,332 B2Granted
Synthesis of cyclen derivatives
AssigneeGe Healthcare Limited
InventorsOskar Axelsson, Andreas Olsson
Life of this patent
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Abstract
The invention relates to an improved process for preparation of protected DO3A, such as DO3A-tri-t-butyl ester (1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid tri-t-butyl ester). The compound is prepared as a salt. The process includes a work-up procedure giving DO3A-tri-t-butyl ester as a salt of excellent purity.
Claims14
A process for the preparation of compounds of formula (I)
- wherein R represents a carboxylprotective group selected from the group of alkyls, aryls, and substituted aryls;
- X represents a chlorine, bromine or iodine anion or a sulphonate- or phosphate-containing group;
- and
- y represents an integer of from 1 to 4;
- comprising the steps:
- (1) reacting cyclen and an activated acetic acid ester to prepare a mixture;
- (2) adjusting the pH of the mixture to 9.0±0.5;
- (3) adding a salt to the mixture;
- (4) collecting the precipitated product,
- wherein step (3) is carried out prior to, or after, step (2).
7 more elements
Dependencies are inferred from the claim text.