Epoxide-Opening and Group-Transfer Reactions Mediated by Monomeric Zirconium Imido Complexes

N-tert-Butylimidozirconocene (Cp2ZrNt-Bu) and its analogue (ebthi)ZrNAr (ebthi = ethylenebis(tetrahydroindenyl), Ar = 2,6-dimethylphenyl) undergo overall cycloaddition reactions at ambient temperature with epoxides that lack accessible β-hydrogens. The process results in addition of the ZrN bond to an epoxide CO bond, leading to azazirconacyclopentanes. The regio- and stereochemistry of the products implicate a stepwise mechanism, with the intermediacy of zwitterions having substantial carbocation character at the substituted carbon of the ring-opened epoxide-derived fragment. The azametallacycles undergo facile cleavage to β-amino alcohols upon addition of mild acid.