Coordinative Chain Transfer Polymerization of Butadiene with Functionalized Aluminum Reagents

Functionalized aluminum alkyls enable effective coordinative chain transfer polymerization with selective chain initiation by the functionalized alkyl. (ω‐Aminoalkyl)diisobutylaluminum reagents (12 examples studied) obtained by hydroalumination of α‐amino‐ω‐enes with diisobutylaluminum hydride promote the stereoselective catalytic chain growth of butadiene on aluminum in the presence of Nd(versatate)(3), Cp*(2)Nd(allyl), or Cp*(2)Gd(allyl) precatalysts and [PhNMe(2)H(+)]/[B(C(6)F(5))(4) (−)]. Carbazolyl‐ and indolylaluminum reagents result in efficient molecular weight control and chain initiation by the aminoalkyl rather than the isobutyl substituent bound to aluminum. As confirmed for (3‐(9H‐carbazol‐9‐yl)propyl)‐initiated polybutadiene (PBD), for example, by deuterium quenching studies, polymer chain transfer by β‐hydride transfer is negligible in comparison to back‐transfer to aluminum.