Synthesis and evaluation of an ester-functional alkoxyamine for nitroxide-mediated polymerization

The ester-functional alkoxyamine 2,2-dimethyl-3-(1-(4-(methoxycarbonyl)phenyl)ethoxy)-4-(4-(methoxycarbonyl)phenyl)-3-azapentane (2) was efficiently synthesized for use as a functional initiator in nitroxide-mediated polymerization. Two equivalents of 1-(4-(methoxycarbonyl)phenyl)ethyl radical were added across the double bond of 2-methyl-2-nitrosopropane to form alkoxyamine 2, which was found to control the polymerization of styrene, isoprene, and n-butyl acrylate. The ester moieties were hydrolyzed for subsequent esterification with 1-pyrenebutanol to form a dipyrene-labeled initiator that was used to probe nitroxide end-group fidelity after styrene polymerization. High retention of nitroxide was confirmed by UV-vis studies over a range of monomer conversions.