Synthesis of alkoxyamine initiators for controlled radical polymerization

On page 2161 of this volume, Hawker and coworkers report a simple and efficient method for the synthesis of alkoxyamine initiators for controlled radical polymerization. The method involves treatment of a styrene derivative with (salen)manganese(III) chloride and an oxidant, trapping of the intermediate adduct with 2,2,6,6-tetramethylpiperidinyloxy (TEMPO), and reduction with sodium borohydride. The method works nicely as a one-pot procedure and provides the target alkoxyamines in yields of ca. 55–75%. An attractive feature of the synthesis is the fact that hydroxyl, ester, halide, and alkene functional groups can be tolerated without loss of yield, suggesting that appropriately-substituted alkoxyamine initiators should become readily available for the preparation of polymers of controlled endgroup functionality.