High-Yield Synthesis of Functionalized Alkoxyamine Initiators and Approach to Well-Controlled Block Copolymers Using Them

Reaction of ethylbenzene, 4-bromo-, 4-(ethoxycarbonyl)-, and 4-methoxyethylbenzenes with di- tert- butyl diperoxyoxalate at 35 °C in the presence of stable nitroxide radicals gave alkoxyamines in 50−91% yields. Lithiation of the 4-bromophenylalkoxyamine and subsequent treatment with DMF gave 4-formylphenylalkoxyamine in 95% yield, and the reduction of the 4-formylphenylalkoxyamine with NaBH 4 yielded 4-(hydroxymethyl)phenylalkoxyamine in 89% yield. Anionic polymerization of butadiene (BD) with sec -BuLi and subsequent termination with 4-formylphenylalkoxyamine gave an end-functionalized poly(butadiene) [poly(BD)]. “Living” radical polymerization of styrene (St) initiated by the functionalized poly(BD) at 120 °C gave a poly(BD)- block -poly(St) with a M w / M n of 1.30. Anionic polymerization of hexamethylcyclotrisiloxane (D 3 ) with 4-lithiophenylalkoxyamine gave poly(D 3 ) with an alkoxyamine moiety at a polymer end. “Living” radical polymerization of St initiated by the functionalized poly(D 3 ) gave poly(D 3 )- block -poly(St) with M w / M n 's of 1.73−1.80.