Multigram synthesis of well-defined extended bifunctional polyethylene glycol (PEG) chains.

A series of novel, well-defined, unsymmetrical poly(ethylene glycol) chains of the type X(OCH(2)CH(2))(n)()Y (where X = protecting group; Y = nucleofuge or a different protecting group; n = 3, 6, 9, 12, 15, 18, and 24) were prepared in high yields by applying orthogonal protecting groups. The purity of the compounds was fully verified by elemental and high-resolution mass spectrometry analyses.