{HEAD ~ The invention} provides {TAIL ~ a method} for preparing a 1 benzotriazolylcarbonate ester of a water soluble and non peptidic polymer by reacting a terminal hydroxyl group of a water soluble and non peptidic polymer with dicarbonate in the presence of an amine base and an organic solvent 
provides
{ HEAD ~ The invention } provides { TAIL ~ a method } for preparing a 1 benzotriazolylcarbonate ester of a water soluble and non peptidic polymer by reacting a terminal hydroxyl group of a water soluble and non peptidic polymer with dicarbonate in the presence of an amine base and an organic solvent
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