IAN Amines: Chiral C2-Symmetric Zirconium(IV) Complexes from Readily Modified Axially Chiral C1-Symmetric β-Diketimines

Abstract

A general synthesis of β-diketimines derived from Isoquinoline and AminoNaphthalene components (IAN amines) is reported. Beginning from inexpensive 2-naphthol and isoquinoline, the sequence of reactions leading to R-IAN amines is convergent, short, and high-yielding. Several new derivatives are reported (e.g., R = Bn, iPr, tBu, Ph, 2,6-Me2Ph, 2,6-iPr2Ph, 2-Np). All of these were complexed to zirconium(IV) by transamination with Zr(NMe2)4, and in all cases 1:1 R-IAN:Zr complexes immediately formed at 25 °C. Except in cases of severe steric hindrance (iPr-IAN and 2,6-Me2Ph), the corresponding 2:1 IAN:Zr complexes formed at temperatures ranging from 25 to 100 °C in toluene. A feature conserved among all 2:1 IAN:Zr complexes was a remarkable degree of diastereoselectivity favoring a C2-symmetric bis(β-diketiminate) isomer bearing cis-NMe2 and cis-pyridyl ligands. Although all complexations were performed from rac-IAN, the resulting complexes are composed solely of homochiral ligands. The configurational integ...