Pincer-Nickel Catalyzed Selective Guerbet-Type Reactions

Organometallics, Journal Year: 2021, Volume and Issue: 40(16), P. 2870 - 2880

Published: Aug. 5, 2021

We report here the synthesis and characterization of a series NNN pincer-nickel complexes type (R2NNN)NiCl2(CH3CN) (R = iPr, tBu, Cy, Ph, p-F-C6H4) based on bis(imino)pyridine ligands. In solution, these are found to be equilibrium mixtures containing one two pincer ligands, respectively. While crystal structure former was reported by us recently for R we latter in this study p-F-C6H4. The considered pincer-Ni have been successfully employed accomplish catalytic β-alkylation several secondary alcohols with variety benzyl at 140 °C high yields unprecedented turnovers. A maximum 92% yield β-alkylated product 18 400 TON obtained reaction alcohol 1-(4-(trifluoromethyl)phenyl)ethane-1-ol presence 0.005 mol % (Ph2NNN)NiCl2(CH3CN) 5 NaOtBu after 24 h. exhibits zero-order dependence rate catalyst concentration first-order base, alcohol, 1-phenyl ethanol which points base-mediated aldol condensation as rate-determining step. Most intermediates involved catalysis identified HRMS. To best our knowledge, is first catalyzed and, hitherto, such turnovers not homogeneous molecular nickel-based catalyst.

Language: Английский

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Recent advances in C/N-alkylation with alcohols through hydride transfer strategies

Organic & Biomolecular Chemistry, Journal Year: 2022, Volume and Issue: 20(39), P. 7713 - 7745

Published: Jan. 1, 2022

Recent advances in C/N alkylation using alcohols as alkylating reagents via hydrogen-shuttle methodologies: Borrowing Hydrogen, Acceptorless Dehydrogenative Coupling, and Base-mediated Hydride Transfer.

Language: Английский

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NNN Pincer-Manganese-Catalyzed Guerbet-Type β-Alkylation of Alcohols under Microwave Irradiation

Organometallics, Journal Year: 2023, Volume and Issue: 42(14), P. 1818 - 1831

Published: June 24, 2023

A series of manganese carbonyl complexes based on bis(imino)pyridine ligands the type R2NNN (R = Cy, iPr, Ph, p-FC6H4) were synthesized. While complex appears to be an NN bidentate-Mn(I) triscarbonyl species in solid state, solution, there is a gradual loss carbon monoxide leading first NNN pincer-Mn(I) biscarbonyl complex, which finally disproportionates pincer-Mn(II) dibromide and pincer-Mn(0) complex. Evidence for this transformation has been obtained from single-crystal X-ray diffraction, IR, EPR, HRMS analysis. The apparently faster with cyclohexyl-substituted than others. considered (0.05 mol %) utilized catalyzing β-alkylation secondary alcohols at 140 °C air under conventional heating (12 h), as well microwave (2 h) presence 2.5 % NaOtBu. Among complexes, catalyst (p-FC6H4NNN)Mn(CO)2Br was found highly efficient. heating, maximum 92% (1840 TON 153 TOs/h) β-alkylated product obtained; provided 85% yield (1700 850 just 2 h. catalytic system successfully implemented alkylate several other alcohols, (35 examples). analyses indicate intermediates cycle both pincer-Mn(II)/Mn(0) couple. Deuterium labeling studies point involvement C–H bond activation rate-determining step (RDS) kinetic isotope effect (KIE) 9.0.

Language: Английский

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Efficient net transfer-dehydrogenation of glycerol: NNN pincer–Mn and manganese chloride as a catalyst unlocks the effortless production of lactic acid and isopropanol

Dalton Transactions, Journal Year: 2024, Volume and Issue: 53(30), P. 12698 - 12709

Published: Jan. 1, 2024

Herein, a series of pincer-Mn complexes based on bis(imino)pyridine ligands the type

Language: Английский

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Nickel-catalyzed sustainable synthesis of N-heterocycles through dehydrogenative coupling of alcohols

Tetrahedron Letters, Journal Year: 2021, Volume and Issue: 81, P. 153326 - 153326

Published: Aug. 20, 2021

Language: Английский

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Nickel(i)-catalyzed (de)hydrogenative coupling of amines and alkyl heteroarenes with alcohols

Green Chemistry, Journal Year: 2022, Volume and Issue: 24(19), P. 7368 - 7375

Published: Jan. 1, 2022

A novel cationic nickel( i ) complex exhibiting extremely high efficiency toward the (de)hydrogenative N -alkylation of amines and olefination alkyl heteroarenes by alcohols is reported.

Language: Английский

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Acceptorless or Transfer Dehydrogenation of Glycerol Catalyzed by Base Metal Salt Cobaltous Chloride – Facile Access to Lactic Acid and Hydrogen or Isopropanol

Chemistry - A European Journal, Journal Year: 2023, Volume and Issue: 30(1)

Published: Oct. 9, 2023

The dehydrogenation of glycerol to lactic acid (LA) under both acceptorless and transfer conditions using readily available, inexpensive, environmentally benign earth-abundant base metal salt CoCl

Language: Английский

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Pincer–Ruthenium-Catalyzed β-Methylation of Alcohols

Organometallics, Journal Year: 2023, Volume and Issue: 42(21), P. 3138 - 3152

Published: Oct. 30, 2023

The synthesis and characterization of three NNN pincer–Ru complexes based on bis(imino)pyridine ligands have been reported. These along with other previously reported catalysts 2,6-bis(benzimidazol-2-yl)pyridine employed to accomplish the β-methylation 2-phenylethanol selective β-dimethylation 1-phenylethanol using methanol as an alkylating agent. In general, pincer–ruthenium complex [(MeBim2NNN)RuCl(PPh3)2]Cl dimethyl-substituted ligand was found be most efficient among considered catalysts. Under best conditions, in (0.5 mol %)-catalyzed reactions presence 0.75 equiv KOH 7.5 methanol, up 92% yield β-methylated obtained at 140 °C. On hand, could achieved 2 Na 24.8 methanol. developed synthetic protocol is generic nature applied about 35 substrates. reaction has also probed from a mechanistic point view. While mercury poisoning experiments revealed catalyzed by well-defined molecular catalysts, kinetic indicated that rate product formation linear dependence concentrations both catalyst 2-phenylethanol. DFT studies complement observed secondary isotope effect (KIE) 1.56 suggest dehydrogenolysis involving σ-bond metathesis Ru–H species leading evolution hydrogen rate-determining step barrier 24.06 kcal/mol. Ru–OMe species, being lowest-energy intermediates catalytic cycle, are likely resting state cycle detected NMR HRMS analysis.

Language: Английский

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Nickel Pincer Complexes Catalyzed Sustainable Synthesis of 3,4-Dihydro-2H-1,2,4-benzothiadiazine-1,1-dioxides via Acceptorless Dehydrogenative Coupling of Primary Alcohols

The Journal of Organic Chemistry, Journal Year: 2024, Volume and Issue: 89(4), P. 2494 - 2504

Published: Feb. 7, 2024

We report the atom-economic and sustainable synthesis of biologically important 3,4-dihydro-2H-1,2,4-benzothiadiazine-1,1-dioxide (DHBD) derivatives from readily available aromatic primary alcohols 2-aminobenzenesulfonamide catalyzed by nickel(II)-N∧N∧S pincer-type complexes. The synthesized nickel complexes have been well-studied elemental spectroscopic (FT-IR, NMR, HRMS) analyses. solid-state molecular structure complex 2 has authenticated a single-crystal X-ray diffraction study. Furthermore, series (24 examples) utilizing 3 mol % Ni(II) catalyst through acceptorless dehydrogenative coupling benzyl with benzenesulfonamide. Gratifyingly, catalytic protocol is highly selective yield up to 93% produces eco-friendly water/hydrogen gas as byproducts. control experiments plausible mechanistic investigations indicate that in situ generated aldehyde benzenesulfonamide leads desired product. In addition, large-scale one thiadiazine unveils synthetic usefulness current methodology.

Language: Английский

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Production of Lactic Acid via Catalytic Transfer Dehydrogenation of Glycerol Catalyzed by Base Metal Salt Ferrous Chloride and Its NNN Pincer-Iron Complexes

Inorganic Chemistry, Journal Year: 2024, Volume and Issue: 63(33), P. 15294 - 15310

Published: Aug. 7, 2024

NNN-Bis(imino) pyridine-based pincer-Fe(II) complexes with an expected trigonal bipyramidal (TBP) geometry equilibrated to a rearranged ion pair of octahedral dicationic Fe complex containing two bis(imino)pyridine ligands that are neutralized by tetrahedral dianionic-[FeCl4]2–. Single-crystal X-ray diffraction (SCXRD), high-resolution mass spectrometry (HRMS), and UV–visible (UV–vis) studies suggested the equilibrium was dictated sterics R group on imine N, less-crowded groups tilting bulky ones favoring TBP geometry. Electron paramagnetic resonance (EPR) Evan's magnetic moment measurements indicated were Fe(II) in high-spin state. In solution, over period 7 days, these oxidized mixture low-spin Fe(III) species. These found be highly active toward transformation biodiesel waste glycerol value-added lactic acid (LA). Particularly, (Ph2NNN)FeCl2 (0.1 mol %) gave 91% LA 99% selectivity at 140 °C using 1.2 equiv NaOH. With 0.0001 % (Ph2NNN)FeCl2, very high turnovers (74% LA, 98% selectivity, 740 000 turnover number (TON) 4405 per hour (TOs/h)) obtained after days. EPR species catalyst, few which detected HRMS. Experiments Hg suggestive mostly homogeneous molecular nature catalyst minor contribution from heterogeneous nanoparticles.

Language: Английский

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