Patent ID: 8349800

Claim:
A method of preparing a compound, said method comprising contacting a polymeric reagent with an amine-containing biologically active agent that is either a von Willebrand Factor moiety or a Factor VIII moiety to form a reaction mixture under conditions suitable to form a releasable covalent attachment between the polymeric reagent and an amino-group of the biologically active agent, wherein the polymeric reagent has the following structure: wherein: POLY 1 is a first water-soluble polymer; POLY 2 is a second water-soluble polymer; X 1 is a first spacer moiety; X 2 is a second spacer moiety; H α is an ionizable hydrogen atom; R 1 is H or an organic radical; R 2 is H or an organic radical; (a) is either zero or one; (b) is either zero or one; R e1 , when present, is a first electron altering group; R e2 , when present, is a second electron altering group; and (FG) is a functional group capable of reacting with an amino group of the biologically active agent to form a releasable linkage.