Patent ID: 7790835

Claim:
A method of forming a polymer intermediate useful in the synthesis of a maleimide functionalized polymer, the method comprising the steps of: i) providing a water soluble and non-peptidic polymer comprising at least one functional group; and ii) reacting the functional group of the polymer with a Diels-Alder adduct reagent comprising an imido ring or anhydride ring to form a polymer intermediate of the following structure wherein: POLY is the water soluble and non-peptidic polymer (i) terminating in either a hydroxyl group or end capping group selected from the group consisting of methoxy, ethoxy, butyloxy and benzyloxy, (ii) having a weight average molecular weight of greater than 4,000 Daltons and less than about 300,000 Daltons, and (iii) is selected from the group consisting of poly(alkylene glycol), poly(olefinic alcohol), poly(vinylpyrrolidone), poly(hydroxyalkylmethacrylamide), poly(hydroxyalkylmethacrylate), poly(α-hydroxyacetic acid), poly(acrylic acid), poly(vinyl alcohol), polyphosphazene, polyoxazoline, poly(N-acryloylmorpholine), and copolymers or terpolymers thereof; L is an optional linkage; X is selected from the group consisting of alkylene, substituted alkylene, alkenylene, substituted alkenylene, —C(O)—, heteroatom, substituted heteroatom and two hydrogens, wherein one of the two hydrogens attached to the carbon bearing R 1 and the other to the carbon bearing R 4 ; and each of R 1 , R 2 , R 3 and R 4 is independently selected from the group consisting of H, halo, hydroxyl, carboxyl, carboxylalkyl, thiol, alkylthio, acyl, acyloxy, nitro, cyano, azido, trihalomethyl, alkyl, substituted alkyl, cycloalkyl, substituted cycloalkyl, alkoxy, aryl, substituted aryl, heterocycle, substituted heterocycle, heteroaryl, and substituted heteroaryl.