Unsymmetrical, oxazolinyl-containing achiral and chiral NCN pincer ligand precursors and their complexes with palladium(II)

Hao, Xin‐Qi; Wang, Yanan; Liu, Jun-Rui; Wang, Kunlun; Gong, Jun‐Fang; Song, Mao‐Ping

doi:10.1016/j.jorganchem.2009.09.031

Cited by 50 publications

(11 citation statements)

References 30 publications

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“…In fact, to the best of our knowledge, up to now the only one example on the NCN¢ pincer Pd complexes has been reported from our group. 78 As shown in Scheme 11, starting from commercially available isophthalaldehyde the achiral or chiral (oxazolinyl)pyrazole-( 39) and (oxazolinyl)amine-containing (41) NCN¢ pincer ligand precursors were prepared in four steps including selective reduction of one aldehyde by NaBH 4 , bromination with PBr 3 , nucleophilic substitution with 3,5-dimethylpyrazole, pyrazole or diethylamine and conversion of the other aldehyde group to 2oxazoline. The subsequent employment of Pd(OAc) 2 to promote the direct cyclopalladation of the ligands provided the desired unsymmetrical NCN¢ pincer Pd(II) complexes 40a-d and 42.…”

Section: Ncn¢ Pincer Pd(ii) Complexesmentioning

confidence: 99%

Symmetrical and unsymmetrical pincer complexes with group 10 metals: synthesis via aryl C–H activation and some catalytic applications

et al. 2011

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Aryl-based pincer metal complexes with anionic terdentate ligands have been widely applied in organic synthesis, organometallic catalysis and other related areas. Synthetically, the most simple and convenient method for the construction of these complexes is the direct metal-induced C(aryl)-H bond activation, which can be fulfilled by choosing the appropriate functional donor groups in the two side arms of the aryl-based pincer preligands. In this perspective, we wish to summarize some results achieved by our group in this context. Successful examples include symmetrical chiral bis(imidazoline) NCN pincer complexes with Ni(II), Pd(II) and Pt(II), bis(phosphinite) and bis(phosphoramidite) PCP pincer Pd(II) complexes, unsymmetrical (pyrazolyl)phosphinite, (amino)phosphinite and (imino)phosphinite PCN pincer Pd(II) complexes, chiral (imidazolinyl)phosphinite and (imidazolinyl)phosphoramidite PCN pincer complexes with Ni(II) and Pd(II) as well as unsymmetrical (oxazolinyl)amine and (oxazolinyl)pyrazole NCN' pincer Pd(II) complexes. Among them, the P-donor containing complexes are efficiently synthesized by the "one-pot phosphorylation/metalation" method. The obtained symmetrical and unsymmetrical pincer complexes have been used as catalysts in Suzuki-Miyaura reaction (Pd), asymmetric Friedel-Crafts alkylation of indole with trans-β-nitrostyrene (Pt) as well as in asymmetric allylation of aldehyde and sulfonimine (Pd). In the Suzuki couplings conducted at 40-50 °C, some unsymmetrical Pd complexes exhibit much higher activity than the related symmetrical ones which can be attributed to their faster release of active Pd(0) species resulting from the hemilabile coordination of the ligands. Literature results on the synthesis of some related pincer complexes as well as their activities in the above catalytic reactions are also presented.

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Section: Ncn¢ Pincer Pd(ii) Complexesmentioning

confidence: 99%

Symmetrical and unsymmetrical pincer complexes with group 10 metals: synthesis via aryl C–H activation and some catalytic applications

et al. 2011

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“…For background to pincer palladium complexes, see: van Koten & Gebbink (2011); Moreno et al (2010); Selander & Szabó (2011). For palladium complexes with NCN pincer ligands, see: Hao et al (2010); Young et al (2011). For studies on the chemistry of bis(oxazole) pincer palladium complexes, see: Luo et al (2007Luo et al ( , 2011; Xu et al (2011).…”

Section: Related Literaturementioning

confidence: 99%

“…Considerable attention has recently been devoted to pincer-Pd complexes due to their catalytic abilities (Ghorai et al, 2012;van Koten & Gebbink, 2011;Moreno et al, 2010;Selander & Szabó, 2011). We are interested in the NCN type of pincer-Pd complexes (Luo et al, 2007(Luo et al, , 2011(Luo et al, , 2012Xu et al, 2011) as a variety of nonphosphine pincer catalytic system, that contains two nitrogen atoms as donating sites in the coordination sphere (Hao et al, 2010;Young et al, 2011) The title compound was conveniently synthesized from the reaction of Pd(dba) 2 (dba = dibenzylideneacetone) with 1bromo-2,6-bis(5-ethoxyoxazol-2-yl)-4-methoxy benzene in dry benzene under reflux in an argon atmosphere. As a result, the title compound was isolated with 84% yield.…”

Section: S1 Commentmentioning

confidence: 99%

[2,6-Bis(5-ethoxy-1,3-oxazol-2-yl)-4-methoxyphenyl-κ³N,C¹,N′]bromidopalladium(II)

Nan¹,

Tan²,

Luo³

2012

Acta Cryst E

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In the title compound, [PdBr(C17H17N2O5)], the PdII atom is coordinated by an N,C 1,N′-tridentate pincer ligand and a Br atom in a distorted square-planar geometry. In the crystal, molecules are connected by C—H⋯Br and C—H⋯O hydrogen bonds, and π–π interactions between the oxazole and benzene rings [centroid–centroid distance = 3.7344 (19) Å], resulting in a three-dimensional supramolecular structure.

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“…Depending on the latter structural features, interaction with substrates and/or the stabilization of reaction intermediates can be facilitated [ 103 , 104 ]. In fact, an increasing number of reports on the application of these terdentate complexes as catalysts or pre-catalysts for a number of synthetic transformations have been published, including recent papers on cross-coupling reactions catalyzed by pincer compounds [ 105 , 106 , 107 , 108 , 109 , 110 , 111 , 112 , 113 , 114 , 115 , 116 , 117 , 118 , 119 , 120 ]. In this regard, inter- and intramolecular direct (hetero)arylations have been carried out in the presence of several pincer complexes.…”

Section: Introductionmentioning

confidence: 99%

Direct Arylation in the Presence of Palladium Pincer Complexes

et al. 2021

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Direct arylation is an atom-economical alternative to more established procedures such as Stille, Suzuki or Negishi arylation reactions. In comparison with other palladium sources and ligands, the use of palladium pincer complexes as catalysts or pre-catalysts for direct arylation has resulted in improved efficiency, higher reaction yields, and advantageous reaction conditions. In addition to a revision of the literature concerning intra- and intermolecular direct arylation reactions performed in the presence of palladium pincer complexes, the role of these remarkably active catalysts will also be discussed.

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Unsymmetrical, oxazolinyl-containing achiral and chiral NCN pincer ligand precursors and their complexes with palladium(II)

Cited by 50 publications

References 30 publications

Symmetrical and unsymmetrical pincer complexes with group 10 metals: synthesis via aryl C–H activation and some catalytic applications

Symmetrical and unsymmetrical pincer complexes with group 10 metals: synthesis via aryl C–H activation and some catalytic applications

[2,6-Bis(5-ethoxy-1,3-oxazol-2-yl)-4-methoxyphenyl-κ³N,C¹,N′]bromidopalladium(II)

Direct Arylation in the Presence of Palladium Pincer Complexes

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Unsymmetrical, oxazolinyl-containing achiral and chiral NCN pincer ligand precursors and their complexes with palladium(II)

Cited by 50 publications

References 30 publications

Symmetrical and unsymmetrical pincer complexes with group 10 metals: synthesis via aryl C–H activation and some catalytic applications

Symmetrical and unsymmetrical pincer complexes with group 10 metals: synthesis via aryl C–H activation and some catalytic applications

[2,6-Bis(5-ethoxy-1,3-oxazol-2-yl)-4-methoxyphenyl-κ3N,C1,N′]bromidopalladium(II)

Direct Arylation in the Presence of Palladium Pincer Complexes

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[2,6-Bis(5-ethoxy-1,3-oxazol-2-yl)-4-methoxyphenyl-κ³N,C¹,N′]bromidopalladium(II)