Dao Zhang

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Name: 张道; Dao Zhang

Organization: Fudan University , China

Department: Department of Chemistry

Title: Associate Professor(PhD)

TOPICS

Inorganic Chemistry

Functional Complex

Organic Chemistry

Asymmetric Synthesis suzuki-miyaura Coupling

Chemicals
References

Chiral linker-bridged bis-N-heterocyclic carbenes: design, synthesis, palladium complexes, and catalytic properties

Co-reporter:Dao Zhang, Yu He and Junkai Tang

Dalton Transactions 2016 vol. 45(Issue 29) pp:11699-11709

Publication Date(Web):12 May 2016

DOI:10.1039/C6DT00984K

A series of chiral bis(benzimidazolium) salts 10–19 with (1R,2R)-cyclohexene, (1R,2R)-diphenylethylene and (aR)-binaphthylene linkers have been designed and synthesized in 30–94% yield. Ten chiral bis(NHC) palladium complexes 20–28 have been synthesized and characterized by NMR, HRMS, elemental analysis and further confirmed by X-ray single crystal analysis. These bis(NHC)-Pd complexes showed obviously different catalytic properties in the asymmetric Suzuki–Miyaura coupling reactions. The (1R,2R)-cyclohexene-bridged bis(NHC)-Pd complex, (R,R)-23, achieved the highest yield of 90%, while complex (aR)-28, with a binaphthylene linker, showed the best enantioselectivity of 60 ee%. The structural analysis of these complexes suggested that such difference of catalytic performance has a close relationship with their coordination surroundings around metal centres.

Brønsted Base-Induced Rearrangement and Nucleophilic Addition of O/N-Functionalized NHCs and Relative Group 4 Metal Complexes for Ethylene Polymerization Catalysis

Co-reporter:Li Wan and Dao Zhang

Organometallics 2016 Volume 35(Issue 2) pp:138-150

Publication Date(Web):January 8, 2016

DOI:10.1021/acs.organomet.5b00862

The O/N-functionalized NHC precursors 1-[RNHC(O)CH2]-3-[2-OH-3,5-tBu2-(C6H2)CH2]-imidazolium bromide, [H3(1a–f)]Br (a: R = 2,6-iPr2-(C6H3); b: R = 2,4,6-Me3-(C6H2); c: R = 2,6-Me2-(C6H3); d: R = 4-Me-(C6H4); e: R = 4-Cl-(C6H4); f: R = tBu), have been synthesized and characterized. Reactions between the aryloxy/amido-NHC precursors [H3(1a–e)]Br and Ag2O resulted in the NHC rearrangement to compounds [2-OH-3,5-(tBu)2-(C6H2)CH2][R]NC(O)-CH2-(C3N2H3) (4a–e) in 68–89% yield. The preliminary study suggested that, after deprotonation, the o-quinone methide (o-QM) intermediate was in situ generated by the C–N cleavage and proton transfer of the resultant aryloxybenzyl NHCs, followed by the nucleophilic attack of o-QM to the nitrogen atom of the amido group. Treatment of salicylaldimine-functionalized NHC precursor 1-iPr-3-[2-HO-C6H2-3,5-tBu2-C(H)═N-CH2CH2]-imidazolium bromide, [H2(2)]Br, with sodium hydride and group 4 metal sources MCl4(THF)2 (M = Ti, Zr) step by step afforded rare zwitterionic complexes [M(13)Cl4] (M = Ti, 10; Zr, 11) in 50–53% yield. The formation of phenolate-amine 13 was attributed to the nucleophilic addition of the formed NHC to the imine carbon after deprotonation. The corresponding products 4a and {[Ti(13)Cl4]2(μ-O)} (12) from the controlled hydrolysis of 10 have been confirmed by X-ray single-crystal analysis. Two novel NHC precursors, {H2(5)}Br and [H3(7)]Br, together with silver complex [Ag2(5)2] (6) were conveniently derived. Several relative group 4 metal complexes, [MX2(k2-N,O-OC6H2-3,5-tBu2-C(H)═N–-CH2CH2-Im)2][Br]2 (M = Zr, X = Cl, 8; M = Hf, X = OSiMe3, 9) and [Ti(7)Cl2] (14), have been prepared and tested for ethylene polymerization with MAO as cocatalyst. Complex 14 showed the highest catalytic activity of up to ca. 114 kg PE/(mol Ti·h·atm) to produce linear polymer.

N-heterocyclic carbene (NHC) complexes of group 4 transition metals

Co-reporter:Dao Zhang and Guofu Zi

Chemical Society Reviews 2015 vol. 44(Issue 7) pp:1898-1921

Publication Date(Web):22 Jan 2015

DOI:10.1039/C4CS00441H

Since the discovery of a stable N-heterocyclic carbene (NHC), the use of NHCs in chemistry has developed rapidly over the past two decades. These interesting compounds are predominantly employed in organometallic chemistry as ligands for various metal centers, and as organocatalysts for a variety of transformations. In particular, the NHC transition metal complexes have received widespread attention, and significant progress has been made in the development of group 4 NHC-complexes in the last few years. These group 4 NHC-complexes are of interest because of their unique structural properties, and their potential application in organic transformations and catalysis. This review covers the superior design strategies for NHC ligands to stabilize early transition metals and well-defined group 4 metal complexes with mono- and multi-dentate NHC ligands. In this context, four types of NHC-complexes, i.e., carbon-functionalized NHCs, nitrogen-functionalized NHCs, oxygen-functionalized NHCs and nitrogen/oxygen-functionalized unsymmetric NHCs, are described. In addition, the use of group 4 NHC-complexes as catalysts in olefin (co)polymerization, ring-opening polymerization of rac-lactide, copolymerization of epoxides and CO2, as well as hydroamination/cyclization of aminoalkenes, is presented. Furthermore, limitations and challenges are discussed.

Palladium catalyzed asymmetric Suzuki–Miyaura coupling reactions to axially chiral biaryl compounds: Chiral ligands and recent advances

Co-reporter:Dao Zhang, Quanrui Wang

Coordination Chemistry Reviews 2015 Volume 286() pp:1-16

Publication Date(Web):1 March 2015

DOI:10.1016/j.ccr.2014.11.011

•Pd catalyzed asymmetric Suzuki–Miyaura couplings (Pd-ASMC) is a valuable method to axially chiral biaryl compounds.•Summary of three main categories of relevant chiral auxiliary ligands applied in Pd-ASMC.•Evaluation of catalytic performance of chiral ligand systems in Pd-ASMC.•Discussion of the correlation between ligand coordination, catalyst activity and enantioselectivity.•Perspective on potential for new developments in the field of Pd-ASMC.Axially chiral biaryls exist widely in bioactive natural products and auxiliary ligands for homogeneous catalysis. The particular spatial arrangement of the two aromatic rings in the specific space determines their unique properties; therefore, how to effectively control their absolute configuration is the key issue. Within the last decade, the synthesis of axially chiral biaryls has been a research topic of great interest. Asymmetric biaryl coupling controlled by chiral palladium catalysts was first reported in 2000 and has greatly advanced the chemistry of transition-metal-catalyzed cross-coupling reactions. Most notably, some novel chiral auxiliary ligands such as ferrocene- or biaryl backbone-containing monophosphine, bisphosphines, bis-hydrazones, hydrazone–phosphines, diene and NHC ligands have been applied to this reaction. At the same time a broad range of aryl electrophiles such as phenols, aryl ethers, esters, carbonates, carbamates, sulfamates, phosphates, phosphoramides, phosphonium salts, and fluorides can now be coupled efficiently with boron reagents to afford functionalized axially chiral biaryl products with good to excellent yields and enantioselectivities in the presence of chiral palladium catalysts. In this review, we would like to summarize three main categories of chiral catalysts with discussion of their advantages and limitation.

Chiral 1,2-Cyclohexane-Bridged Bis-NHC Palladium Catalysts for Asymmetric Suzuki–Miyaura Coupling: Synthesis, Characterization, and Steric Effects on Enantiocontrol

Co-reporter:Yinle Li, Junkai Tang, Jun Gu, Quanrui Wang, Peipei Sun, and Dao Zhang

Organometallics 2014 Volume 33(Issue 4) pp:876-884

Publication Date(Web):February 7, 2014

DOI:10.1021/om400825e

The series of chiral 1,2-cyclohexane-bridged bis-N-heterocyclic carbene ligand precursors H2[(1R,2R)-(1a–i)]Br with different substituent groups and their neutral and cationic diaqua palladium complexes, namely {Pd[(1R,2R)-(1a–i)]Br2} (2a–i), {Pd[(1R,2R)-(1a)]X2} (X = Cl (3), OAc (4-OAc), OC(O)CF3 (4-OCH(O)CF3)), and {Pd[(1R,2R)-(LOMe)](OH2)2}X2 (X = OTf (5-OTf), SbF6 (5-SbF6)) have been prepared in moderate to good yields. These chiral palladium complexes were fully characterized by elemental analysis, high-resolution mass spectra, 1H and 13C NMR, and optical rotation determinations. The crystal structures of the chiral complexes 2a and 5-OTf were further confirmed to adopt a distorted-square-planar coordination geometry around the palladium center. The obtained chiral NHC-Pd compounds were able to catalyze the asymmetric Suzuki–Miyaura couplings of aryl halides with arylboronic acids in good yields (up to 96%) and moderate enantioselectivities (up to 64% ee). The coligand and steric effects were studied carefully. The coligands, including Br–, Cl–, AcO–, CF3COO–, and water molecules, have little influence on the catalytic results. However, a strong steric effect of the two aromatic substituents R on the enantiocontrol has been proved in the catalytic asymmetric Suzuki–Miyaura coupling reaction. The highest enantioselectivity of 64% ee could be achieved under the standard reaction conditions.

Direct synthesis of cis-dihalido-bis(NHC) complex of nickel(II) and catalytic application in olefin addition polymerization: Effect of halogen co-ligands and density functional theory study

Co-reporter:Dao Zhang, Sen Zhou, Zhiming Li, Quanrui Wang and Linhong Weng

Dalton Transactions 2013 vol. 42(Issue 33) pp:12020-12030

Publication Date(Web):22 May 2013

DOI:10.1039/C3DT50957E

Two novel amine-containing N-heterocyclic carbene ligand precursors [H(1a–b)]Br have been prepared in good yield and fully characterized. Direct syntheses of cis- and trans-dihalido-bis(NHC) nickel complexes [Ni(NHC)2X2] (X = Cl, Br) are reported. The solid structures of trans-[Ni(1a–b)2Br2] (2a–b) and cis-[Ni(1a)2Cl2] (3) were determined by single-crystal X-ray analysis and 3 was found to be the first example of cis-configuration coordination of monodentate NHC ligands to a metal center for dihalido-bis(NHC) nickel complexes. DFT calculations were conducted to determine the energy difference between cis- and trans-isomers of complexes 2a and 3 bearing bromide and chloride co-ligands. The cis-[Ni(1a)2Cl2] (cis-3) is 1.77–1.55 kcal mol−1 lower in energy than its trans-isomer in polar solvents including CH2Cl2 and THF, while the trans-[Ni(1a)2Br2] (trans-2a) is more stable than the cis-isomer similarly in the gas phase. The cis nickel complex 3 with two coordinated monodentate NHCs was tested for olefin addition polymerization at standard conditions. It was found that cis-3 was inactive in ethylene polymerization but showed moderate catalytic activities (0.5–3.0 × 106 g of PNB (mol of Ni)−1 h−1) in the addition polymerization of norbornene in the presence of methylaluminoxane (MAO) as cocatalyst.

trans-1,2-Diphenylethylene Linked IsoindolineSalicylaldiminato Nickel(II) Halide Complexes: Synthesis, Structure, Dehydrogenation, and Catalytic Activity toward Olefin Homopolymerization

Co-reporter:Jinyang Wang;Li Wan;Quanrui Wang ;Zhenxia Chen

European Journal of Inorganic Chemistry 2013 Volume 2013( Issue 12) pp:2093-2101

Publication Date(Web):

DOI:10.1002/ejic.201201331

Abstract

Tridentate ligands 4-R¹-6-R²-2-{[trans-2-(isoindolin-2-yl)-1,2-diphenylethylimino]methyl}phenol [R¹ = R² = H, H(L^a); R¹ = R² = tert-butyl, H(L^b); R¹ = Ph, R² = H, H(L^c)] in which a substituted salicylaldimine moiety and an isoindoline are linked by a trans-1,2-diphenylethylene moiety have been prepared. Deprotonation of these tridentate ligands H(L^a)–H(L^c) by NaH at room temperature in tetrahydrofuran (THF), followed by treatment with 1 equiv. of [(PPh₃)₂NiX₂] (X = Cl, Br, I) at room temperature afforded the desired nickel complexes [(L)NiX] (X = Cl, L = L^a, 1; X = Cl, L = L^b, 2; X = Cl, L = L^c, 3; X = Br, L = L^b, 4; X = I, L = L^b, 5) in moderate yields. The structures of 2 and 4 were unequivocally confirmed by single-crystal X-ray diffraction in the solid state. The metal atom has a distorted square-planar coordination geometry and is coordinated to the two nitrogen atoms and one oxygen atom from the tridentate ligand and one halide atom. Dehydrogenation of the chelate tridentate ligand (L^b) in the presence of oxygen afforded the corresponding nickel complexes [(L^b*)NiX] (X = Br, 6; X = I, 7). X-ray analysis showed that in these complexes the two bridged benzylic carbon atoms of (L^b)^– were oxidized and a cis-stilbene moiety, which includes a C=C double bond (1.205–1.268 Å) was formed. These nickel complexes with such trans-1,2-diphenylethylene bridged tridentate ligands proved to be active catalysts for ethylene oligomerization in the presence of methylaluminoxane (MAO) and produced butene and hexene with catalytic activities of 0.49 × 10⁵–3.25 × 10⁵ g mol^–1 Ni h^–1 at 30 °C, under 20 bar of ethylene, and with an MAO/Ni ratio of 250. They were also active catalysts for the homopolymerization of norbornene and styrene and displayed activities of up to 1.89 × 10⁵ and 7.36 × 10⁵ g mol^–1 Ni h^–1, respectively.

Trans-1,2-diphenylethylene bridged salicylaldiminato–isoindoline titanium(IV) chloride complexes: Synthesis, characterization and catalytic polymerization

Co-reporter:Li Wan, Dao Zhang, Quanrui Wang, Zhenxia Chen, Linhong Weng

Journal of Organometallic Chemistry 2013 724() pp: 155-162

Publication Date(Web):

DOI:10.1016/j.jorganchem.2012.11.013

Synthesis, structural characterization and catalytic property of group 4 metal complexes bearing novel salalen-type ligands

Co-reporter:Kun Huang, Sen Zhou, Dao Zhang, Xiang Gao, Quanrui Wang, Yuejian Lin

Journal of Organometallic Chemistry 2013 s 741–742() pp: 83-90

Publication Date(Web):

DOI:10.1016/j.jorganchem.2013.05.036

Synthesis, structure, and catalytic activity of palladium complexes with new chiral cyclohexane-1,2-based di-NHC-ligands

Co-reporter:Gongwo Shigeng, Junkai Tang, Dao Zhang, Quanrui Wang, Zhenxia Chen, Linhong Weng

Journal of Organometallic Chemistry 2012 700() pp: 223-229

Publication Date(Web):

DOI:10.1016/j.jorganchem.2011.12.008

Macrocyclic hexanuclear zirconium(IV) complex bearing a bisaryloxyl N-heterocyclic-carbene ligand: Synthesis, structure, and catalytic properties

Co-reporter:Dao Zhang, Gongwo GengShi, Jinyang Wang, Qin Yue, Wenjun Zheng, Linhong Weng

Inorganic Chemistry Communications 2010 Volume 13(Issue 3) pp:433-435

Publication Date(Web):March 2010

DOI:10.1016/j.inoche.2010.01.005

A rare macrocyclic hexazirconium(IV) complex with bisaryloxyl N-heterocyclic carbene ligand {(L)Zr(OSiMe3)(k2-[N^O])}6 (2) (L=1,3-[3,5-Bu2t-2-O--(C6H2)CH2]2(C3H2N2), H[N^O]=1-[3,5-Bu2t-2-OH-(C6H2)CH2)](C3H3N2)) was prepared from a mononuclear complex [(L)ZrCl2(THF)] (1). Complex 2 was structurally characterized and shows higher catalytic ethylene polymerization activities in the presence of methylaluminoxane (MAO).A rare macrocyclic hexazirconium(IV) bisaryloxyl N-heterocyclic carbene complex {(L)Zr(OSiMe3)(k2-[N^O])}6 (2) (L=1,3-[3,5-Bu2t-2-O--(C6H2)CH2]2(C3H2N2), H[N^O] = 1-[3,5-Bu2t-2-OH-(C6H2)CH2](C3H3N2)) was prepared and structurally characterized and shows higher catalytic ethylene polymerization activities in the presence of MAO.

Synthesis, characterization and catalytic behaviors of water-soluble phosphine-sulfonato nickel methyl complexes bearing PEG-amine labile ligand

Co-reporter:Dao Zhang, Jinyang Wang, Qin Yue

Journal of Organometallic Chemistry 2010 695(6) pp: 903-908

Publication Date(Web):

DOI:10.1016/j.jorganchem.2009.12.024

Synthesis, characterization of a novel anilido-iminato cobalt (II) complex and its application for addition polymerization of norbornene

Co-reporter:Dao Zhang, Qin Yue, Jinyang Wang, Gongwo Shigeng, Linhong Weng

Inorganic Chemistry Communications 2009 Volume 12(Issue 12) pp:1193-1196

Publication Date(Web):December 2009

DOI:10.1016/j.inoche.2009.09.016

A novel anilido-iminato cobalt complex [(L)Co(μ-Cl)2Li(THF)2] (1) (H(L) = o-(2′,6′-iPr2(C6H3)–NH)(C6H4)CHN–(C6H3)Pr2i-2,6) was synthesized by the reaction of the lithium salt of H(L) with CoCl2 in THF in 57% yield, structurally characterized by NMR and X-ray single crystal diffraction, and its application as a catalyst for the addition polymerization of norbornene in the presence of methylaluminoxane (MAO) was reported.A novel cobalt complex with bulky anilido-iminato ligand was synthesized, structurally characterized by X-ray single-crystal diffraction, and its application as a catalyst for the addition polymerization of norbornene in the presence of methylaluminoxane was reported.

Titanium Complexes Bearing Bisaryloxy-N-heterocyclic Carbenes: Synthesis, Reactivity, and Ethylene Polymerization Study

Co-reporter:Dao Zhang and Nan Liu

Organometallics 2009 Volume 28(Issue 2) pp:499-505

Publication Date(Web):December 15, 2008

DOI:10.1021/om800717h

Reaction of titanium complex [(L)TiX2(THF)] (L = {N,N′-[(5-R-3-tert-Bu-2-O−-C6H2)CH2]2 (C3H2N2)}, R = tert-Bu, La, R = Me, Lb; X = Cl, 1a, 1b; X = Br, La, 2) with 2.0 equiv of PhCH2MgCl or MeLi in diethyl ether gave dimethyl complexes [(L)Ti(CH2Ph)2] (3a, 3b) and [(L)Ti(CH3)2](4a, 4b) by salt metathesis. Dibenzyl titanium complex [(La)Ti(CH2Ph)2] (3a) absorbs dioxygen gas to afford the oxygen-insertion product [(La)Ti(OCH2Ph)2] (5) in 57% yield. The reduction of [(La)MBr2(THF)] (2) with 1 equiv of LiBEt3H in toluene gave the titanium(III) species [(La)TiBr(THF)2] (6). The molecular structures of 3b, 4b, 5, and 6 have been confirmed by X-ray single-crystal analysis. The solid state structures of these compounds reveal that these hybrid carbene ligands adopt a transoid conformation to form a pseudotrigonal-bipyramidal (for 3b, 4a, 4b, and 5) or octahedral (for 6) coordination geometry around metal centers. These titanium complexes (1, 2, and 6) showed high activities up to ca. 97 kg PE/(mol Ti·h·atm) for ethylene polymerization in the presence of MAO as coactalyst. The 13C NMR analysis revealed that linear polyethylene with low molecular weight was formed by these NHC titanium complexes. No methyl or other long-chain branch could be observed.

Facile Formation of Hexacyclic [Al3O2Cl] Aluminum and Alkoxide-Bridged Titanium Complexes: Reactions of AlMe3 with [Ti(L)Cl2] [L = 2,2′-Methylenebis(6-tert-butyl-4-methylphenolato)]

Co-reporter:Dao Zhang

European Journal of Inorganic Chemistry 2007 Volume 2007(Issue 19) pp:

Publication Date(Web):10 MAY 2007

DOI:10.1002/ejic.200601227

The titanium dichloride complex [(L)TiCl₂] [L = 2,2′-methylenebis(6-tert-butyl-4-methylphenolato)] (1) reacted with trimethylaluminum (AlMe₃) in a 1:2 ratio to give a trimetallic aluminum complex of the composition [(L)(AlMe₂)₃(μ-Cl)] (2) with a symmetric six-membered ring [Al₃(μ₂-O)₂(μ₂-Cl)] and a four-coordinate aluminum center in the solid state. The reaction of 1 equiv. AlMe₃ gave [(L)TiMeCl] (3), which could absorb O₂ gas to afford the oxygen-insertion product [{(L)TiCl}₂(μ-OMe)₂] (4) with a five-coordinate metal center. Upon reaction of H₂L with AlMe₃, the binuclear, four-coordinate adduct [{(L)AlMe}₂] (5) was formed. Complex 4 supported on MgCl₂ and activated with aluminum alkyls reveals high catalytic activity for ethylene polymerization to produce polymers with molecular weight distributions of ca. 3.1. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Dinuclear Titanium(IV) Complexes Bearing Phenoxide-Tethered N-Heterocyclic Carbene Ligands with cisoid Conformation through Control of Hydrolysis

Co-reporter:Dao Zhang

European Journal of Inorganic Chemistry 2007 Volume 2007(Issue 30) pp:

Publication Date(Web):4 SEP 2007

DOI:10.1002/ejic.200700464

In situ generated N-heterocyclic carbene salt derivative Na₂(L) of 1,3-bis(4,6-di-tert-butyl-2-hydroxybenzyl)imidazolium bromide, [H₃(L)]Br, reacted with 1 equiv. of TiBr₄ at –78 °C to give a titanium complex of the composition [(L)TiBr₂(thf)] (1), while the reaction in a 2:1 ratio under the same conditions afforded bisligand titanium complex [(L)₂Ti] (2). Two oxygen-bridged titanium dimers, {[(L)TiBr]₂(μ-O)} (4) and {[(L)Ti(μ-O)]₂} (5), were obtained by control of hydrolysis of 1 and [(L)Ti(CH₂Ph)₂] (3) in tetrahydrofuran and diethyl ether. The molecular structures of 2, 4, and 5 have been confirmed by X-ray single-crystal analysis. The phenoxide-functionalized NHC ligand adopts transoid conformation in mononuclear complex 2 but rare cisoid conformation in dinuclear complexes 4 and 5. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)