Synthesis, Characterization, and Catalytic Application of Aluminum Anilido‐Oxazolinate Complexes

Abstract

A family of aluminum complexes containing anilido-oxazolinate ligands are described. Reactions of five anilido-oxazolinate ligand precursors, HNPh(TriMe)Oxa, HNPh(DiiPr)Oxa, HNPh(OMe)Oxa, HNPh(SMe)Oxa, or HNPhOxa, with 1 molar equiv. of AlMe(3) in toluene give the aluminum dimethyl complexes (NArOxa)AlMe(2) [Ar = 2,4,6-trimethylphenyl, (NPh(DiiPr)Oxa)AlMe(2) (1); Ar = 2,6-diisopropylphenyl, (NPh(DiiPr)Oxa)AlMe(2) (2); Ar = 2-methoxyphenyl, (NPh(OMe)Oxa)AlMe(2) (3); Ar = 2-methylthiophenyl, (NPh(SMe)Oxa)AlMe(2) (4); Ar = phenyl, (NPhOxa)AlMe(2) (5), respectively]. The molecular structures are reported for compounds 1-4. Their catalytic activities toward the ring-opening polymerization reactions of L-lactide or epsilon-caprolactone in the presence of BnOH are also under investigation. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009

Synthesis and crystal structures of tetrameric [2-(4,4-dimethyl-2-oxazolin-2-yl)anilido]sodium and tris[2-(4,4-dimethyl-2-oxazolin-2-yl)anilido]ytterbium(III)

“…There are 68 structure in the CSD (version 5.39, update of November, 2018;Groom et al, 2016) containing a substituted anilido-oxazoline ligand (R-L1 À ) coordinated to a transition or main group metal. [COZFIH (Coeffard et al, 2009); DEJHIK (Cabeza et al, 2006); EDEBOG (Niwa & Nakada, 2012); EFICON (Bian et al, 2014); FONYAI (Mikami et al, 1999); GIWYES (Chen et al, 2014); GUTTOF (Inagaki et al, 2010); ISEWAG (Abbina et al, 2016); LUNGOS (Bauer et al, 2015a); LUNHAF (Bauer et al, 2015a); MALVUS, MALWAZ and MALWED (Kieltsch et al, 2010); MICTID, MICTOJ, MICTUP, MICVAX and MICVEB (Lu et al, 2013); MUQNAN and MUQNER (Wan et al, 2002); NANFEP, NANFIT, NANFOZ, NANFUF, NANGAM, NANGEQ, NANGIU and NANGOA (Peng & Chen, 2011); OCIHOX, OCIHUD and OCIJAL (Cabaleiro et al, 2001); PUDKUV, PUDLAC, PUDLEG and PUDLIK (Chen et al, 2009a); QIFFES and QIFFIW (Abbina & Du, 2012); RAKTAA (McKeon et al, 2011); RAMFIW, RAMFOC, RAMFUI, RAMGAP and RAMGET ; RAMKEY (Huang et al, 2017); ROGWAM (Nakada & Inoue, 2007); SELVIQ (Nixon & Ward, 2012); SUYQOS, SUYQUY, SUYRAF and SUYREJ (Castro et al, 2001); TIMLIL and TIMLOR (Chen et al, 2007); VOZZOB, VOZZUH and VUBBAX (Bauer et al, 2015b); VUQZAK (O'Reilly et al, 2015); WUGQOF, WUGQUL, WUGRAS and WUGREW (Chen et al, 2009b); XIGYEU (Wu et al, 2018); XOQVEG and XOQVIK (He et al, 2014); XOYVOW, XOYVUC, XOYWAJ, XOYWEN and XOYWIR (Castro et al, 2002)]. In contrast, there is only one structure of an unsubstituted anilido-oxazoline ligand (H-L1 À ) coordinated to a transition metal (Cabeza et al, 2006) and there are no structures of this type with a lanthanide metal.…”

Well‐controlled ring‐opening polymerization of cyclic esters catalyzed by aluminum amido complexes: Kinetics and mechanism

“…Structurally well‐defined organometallic complexes demonstrate prominent superiority in catalyzing the ring‐opening polymerization (ROP) of cyclic esters . Among them, aluminum complexes have attracted significant research focus, especially in the field of isoselective ROP of rac ‐lactide ( rac ‐LA) . Although a variety of aluminum complexes have been explored up to date, in principal, only those having at least one alkoxy ligand could initiate the polymerization of cyclic esters in a well‐controlled manner .…”

Reactions of 4-methylidene-bis(1-phenyl-3-methylpyrazol-5-one) with trimethylaluminum: Synthesis, structure and catalysis for the ring-opening polymerization of ε-caprolactone

“…Each pair of neighboring pyrazole and phenyl rings is parallel and separated in a range 3.865-3.970 Å (distances between ring centroids), indicating the presence of face-toface π-π stacking interactions [17]. The short interplanar π−π separations of the aromatic moieties (pyrazole or phenyl) are believed to provide an additional intramolecular interaction to enhance the stability of tri-adduct Al complex 2 in the solid state.Based on lactone polymerizations catalyzed with dimethyl (salicylaldiminato)-aluminum [18], aluminum anilido-oxazolinate [19] Scheme 1. Synthetic routes for complexes 1 and 2.…”

“…Based on lactone polymerizations catalyzed with dimethyl (salicylaldiminato)-aluminum [18], aluminum anilido-oxazolinate [19] Scheme 1. Synthetic routes for complexes 1 and 2.…”

“…The short interplanar π−π separations of the aromatic moieties (pyrazole or phenyl) are believed to provide an additional intramolecular interaction to enhance the stability of tri-adduct Al complex 2 in the solid state. Based on lactone polymerizations catalyzed with dimethyl (salicylaldiminato)-aluminum [18], aluminum anilido-oxazolinate [19] Scheme 1. Synthetic routes for complexes 1 and 2. or anilido-pyrazolate complexes [20], mono-adduct Al methyl complex 1 was expected to behave as a catalyst toward the ROP of ε-CL in the presence of alcohol.…”