om049897p_si_005.cif (19.25 kB)
IAN Amines: Chiral C2-Symmetric Zirconium(IV) Complexes from Readily Modified Axially Chiral C1-Symmetric β-Diketimines
dataset
posted on 2004-05-10, 00:00 authored by Sarah B. Cortright, John C. Huffman, Ryan A. Yoder, Joseph N. Coalter, Jeffrey N. JohnstonA 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 integrity of Me-IAN and its ability to transfer
asymmetry upon metal coordination was demonstrated in the catalyzed enantioselective
addition of diethylzinc to benzaldehyde. Given the topographical similarity between these
and metallocene complexes, several derivatives were preliminarily evaluated in ethylene
polymerization.
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metallocene complexesconfigurational integrityderivativet Bupyridyl ligandsSymmetricethylene polymerizationenantioselective additionmetal coordinationtransfer asymmetryModified Axially Chiral C 1homochiral ligandscimino N aphthalene componentsi PrNMe 2topographical similarityC 2steric hindranceIAN amines2 Ph
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