Zinc Complexes of <i>β</i>‐Ketoiminato Ligands as Efficient Catalysts for the Synthesis of α‐Amino Nitriles via Strecker Reaction

Das, Suman; Kumar, Ravi; Devadkar, Ajitrao; Panda, Tarun K.

doi:10.1002/ajoc.202000278

Cited by 13 publications

(9 citation statements)

References 121 publications

(79 reference statements)

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“…Dinucleating Ligand H 2 L. The ethylene-bridged βdiketiminate ligand H 2 L (H 2 L = N-(−4-((2-((4-((2,6diisopropylphenyl)imino)pent-2-en-2-yl)amino)ethyl)imino)pent-2-en-2-yl)-2,6-diiso-propylaniline) has been synthesized according to the literature procedure. 65−68 The H 2 L ligand was characterized by 1 H/ 13 C NMR spectroscopy and X-ray single crystal diffraction. An ORTEP drawing of the molecular structure of the H 2 L ligand is shown in Figure S1.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…1 H NMR spectra were recorded at ambient temperature on Bruker Avance-III 400 MHz and Aglient 400 MHz instruments and the spectra were referenced to the TMS signal (0 ppm). 13…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…Calcd for C 44 H 68 N 4 O 2 I 2 Zn 2 (4): C, 49.41; H, 6.41; N, 5.24. Found: C, 49.28; H, 6.38; N, 5.21. sı Supporting InformationThe Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acs.organomet.0c00733.Crystal data and data collection details for compounds 1, 2•C 6 H 14 , 3, and 4•2THF, details of experimental procedures, and 1 H and13 C NMR spectra of the compounds and products (PDF)…”

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confidence: 99%

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Zinc Complexes with an Ethylene-Bridged Bis(β-diketiminate) Ligand: Syntheses, Structures, and Applications as Catalysts in the Borylation of Aryl Iodides

Dang

et al. 2021

Organometallics

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A dinucleating bis(β-diketiminate) ligand with a flexible bridge has been employed to synthesize zinc complexes. The ligand, abbreviated H2L (H2L = N-(4-((2-((4-((2,6-diisopropylphenyl)imino)pent-2-en-2-yl)amino)ethyl)imino)pent-2-en-2-yl)-2,6-diisopropylaniline), was deprotonated with ZnEt2 to afford [LZn2Et2] (1). Reactions of 1 with 2 equiv of BnOH and nBuOH, respectively, gave access to [LZn2(OBn)2]·C6H14 (2·C6H14) and [LZn2(OnBu)2] (3). Treatment of 1 with 2 equiv of I2 in THF produced [LZn2I2(THF)2]·2THF (4·2THF). X-ray single-crystal diffraction analyses revealed that they are all heteroleptic bimetallic compounds with two metal centers being chelated by one ligand set. The structurally similar compounds 1 and 4·2THF possess approximate C 2 symmetry, with two β-diketiminate units being arrayed in head-to-tail antiparallel mode. Thus, the molecular structures of 1 and 4·2THF exhibit a seesaw-like topology. The structures of 2·C6H14 and 3 are almost identical, in which two zinc atoms are shared by two ZnN2C3 six-membered rings, two Zn2ON2C2 seven-membered rings, and one Zn2O2 four-membered ring. Therefore, the metal cores of 2·C6H14 and 3 display a crownlike topology. All complexes are catalytically active for the borylation of aryl iodides with B2Pin2 (B2Pin2 = 4,4,4′,4′,5,5,5′,5′-octamethyl-2,2′-bis(1,3,2-dioxaborolane). Complex 1 shows higher activity in comparison to 2, 3, and 4·2THF. The borylation reactions catalyzed by 1 could proceed under mild conditions and can be applied to a series of substrates with high functional group generality. This methodology thus represents a novel use of β-diketiminate zinc complexes for C–I borylation.

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Section: ■ Results and Discussionmentioning

confidence: 99%

“…1 H NMR spectra were recorded at ambient temperature on Bruker Avance-III 400 MHz and Aglient 400 MHz instruments and the spectra were referenced to the TMS signal (0 ppm). 13…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

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confidence: 99%

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Zinc Complexes with an Ethylene-Bridged Bis(β-diketiminate) Ligand: Syntheses, Structures, and Applications as Catalysts in the Borylation of Aryl Iodides

Dang

et al. 2021

Organometallics

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“…In the course of our research, we have utilized several earth‐abundant metal catalysts in the hydroboration, [46–58] hydroamination, [59–70] and hydrosilylation [71–83] of various functional groups. We have also used metal catalysts in the synthesis of α‐aminonitriles [84] . In this article, in continuation of our earlier work, we explore the application of zinc complexes as catalysts in the formation of benzimidazole and benzothiazole, using several benzylamines, with o ‐phenylenediamine and o ‐mercaptoaniline.…”

Section: Introductionmentioning

confidence: 90%

“…We have also used metal catalysts in the synthesis of α-aminonitriles. [84] In this article, in continuation of our earlier work, we explore the application of zinc complexes as catalysts in the formation of benzimidazole and benzothiazole, using several benzylamines, with o-phenylenediamine and o-mercaptoaniline. We report the synthesis and solid-state structures of a series of zinc complexes supported by the iminopyrrole-morpholine ligand 1.…”

Section: Introductionmentioning

confidence: 98%

Facile Synthesis of Benzimidazole and Benzothiazole Compounds Mediated by a Zinc Precatalyst Supported by an Iminopyrrole‐Morpholine Ligand

2022

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Dedicated to Professor Peter W. Roesky on the occasion of his 55 th Birthday.Three zinc complexes, with the general formula {ksupported by a neutral iminopyrrole-morpholine ligand, were synthesized by the reaction between 1) and anhydrous zinc dihalides (ZnCl 2 , ZnBr 2 , ZnI 2 ) at ambient temperature in dry methanol. The zinc complexes were fully characterized using multinuclear NMR spectroscopic techniques and the molecular structures of complexes 2 a and 2 c in their solid states were determined by single-crystal X-ray diffraction analysis. The zinc diiodo complex (2 c) proved to be a competent precatalyst in the formation of a wide range of benzimidazole and benzothiazole compounds, via aerobic oxidative condensation of several benzylamines with o-phenylenediamine, N-phenyl-o-phenylene-diamine, and o-mercaptoaniline. The benzimidazole and benzothiazole derivatives were successfully characterized using 1 H and 13 C{ 1 H} NMR spectroscopy.

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Zinc Complexes Supported by Hydroxyl‐Containing Schiff‐Base Ligands as Efficient Catalysts for the Borylation of Aryl Iodides

Wu,

Jia,

Chen

et al. 2024

Asian J Org Chem

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The application of a series of hydroxyl‐containing Schiff‐base ligands in the synthesis of zinc complexes is reported. The substituents on the benzene rings, the positions of the C=N double bonds, and the ratio of the ligands to ZnEt2 affect the nuclearities of the zinc compounds. Complexes of various nuclearities were prepared, ranging from trinuclear cluster and dinuclear complexes to mononuclear compounds. Treatment of HL1 (HL1 = 2‐(((1‐(2‐(dimethylamino)ethyl)‐1H‐pyrrol‐2‐yl)methylene) amino)phenol) with one equivalent of ZnEt2 generated a trinuclear compound [(L1)ZnEt]3·0.8Tol (1·0.8Tol). Three dinuclear compounds [(L2)ZnEt]2·Tol (2·Tol), [(L3)ZnEt]2 (3), and [(L4)ZnEt]2 (4), and two mononuclear complexes [(L5)ZnEt] (5) and [(L6)ZnEt] (6) were formed by the reactions of HL2‐HL6, respectively, with ZnEt2. The HL2‐HL6 ligands were obtained by slightly modifying the backbone of the HL1 ligand. Three homoleptic compounds [(L1)2Zn]·THF (7·THF), [(L4)2Zn]·Tol (8·Tol), and [(L5)2Zn] (9) were afforded by changing the ratio of the ligands to ZnEt2 from 1:1 (compounds 1·0.8Tol, 4 and 5) to 1:0.5. The catalytic potential of all nine compounds for the borylation of aryl iodides by B2Pin2 was explored. The catalytic activity of 2·Tol was the highest. The reactions catalyzed by 2·Tol possess the features of high functional group tolerance and broad substrate scope.

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Zinc Complexes of β‐Ketoiminato Ligands as Efficient Catalysts for the Synthesis of α‐Amino Nitriles via Strecker Reaction

Cited by 13 publications

References 121 publications

Zinc Complexes with an Ethylene-Bridged Bis(β-diketiminate) Ligand: Syntheses, Structures, and Applications as Catalysts in the Borylation of Aryl Iodides

Zinc Complexes with an Ethylene-Bridged Bis(β-diketiminate) Ligand: Syntheses, Structures, and Applications as Catalysts in the Borylation of Aryl Iodides

Facile Synthesis of Benzimidazole and Benzothiazole Compounds Mediated by a Zinc Precatalyst Supported by an Iminopyrrole‐Morpholine Ligand

Zinc Complexes Supported by Hydroxyl‐Containing Schiff‐Base Ligands as Efficient Catalysts for the Borylation of Aryl Iodides

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