The present invention provides among other things methods for preparing polymeric reagents, wherein the method comprises (a) providing an aromatic moiety bearing a hydroxy group, a first amino group and a second amino group; (b) reacting a functional group reagent with the hydroxy group to result in a hydroxy group bearing a functional group capable of reacting with an amino group of an active agent and resulting in a hydolyzable carbamate; and (c) reacting a plurality of poly(alkylene glycol) water-soluble polymers bearing a reactive group with the first amino group and second amino group to result in (i) a first amino group bearing a water-soluble polymer through a spacer moiety, and (ii) a second amino group bearing a second water-soluble polymer through a spacer moiety.