Synthesis and ligation ability of mono-aminooxy-functionalized dendrigraft poly-l-lysine (DGL)

A bifunctional tetraethylene glycol (TEG) linker was prepared and used as an initiator for the synthesis of the first two generations of dendrigraft poly-l-lysines (DGL). The key steps involved the desymmetrization of TEG by introduction of an amine group after activation of a terminal hydroxyl group and of a conveniently protected aminooxy functionality at the other end. Initiation of l-lysine N-carboxyanhydride polymerization by the terminal amine yielded generations 1 and 2 of DGL in which a subsequent functionalization of the aminooxy group by ligation with entities bearing an aldehyde group turned out to be feasible.