Optimization and sustainability assessment of a continuous flow Ru-catalyzed ester hydrogenation for an important precursor of a β2-adrenergic receptor agonist

Prieschl, Michael; García-Lacuna, Jorge; Munday, Rachel H.; Leslie, Kevin; O'Kearney‐McMullan, Anne; Hone, Christopher A.; Kappe, C. Oliver

doi:10.1039/d0gc02225j

Cited by 18 publications

(24 citation statements)

References 62 publications

(36 reference statements)

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“…In modern days, it is extremely important to evaluate the advantages and drawbacks of catalytic chemical transformations with the environmental and green aspects based on “The 12 Principles of Green Chemistry”. − To analyze the sustainable and green credentials of the one-step transformation of carbonyl to alcohol, we have selected five different optimized methods for the transfer hydrogenation of acetophenone to 1-phenylethan-1-ol using methanol (Method A), ethanol (Methods B and C), and isopropanol (Methods D and E) as the sacrificial hydrogen sources as well as solvents (Scheme ). The five methods were evaluated with the CHEM21 green metrics toolkit developed by Clark et al The CHEM21 green metrics toolkit is considered as a quantitative extension of “The 12 Principles of Green Chemistry” and many chemical transformations were analyzed using this toolkit. − All those transfer hydrogenations were performed at elevated temperature (70 or 100 °C) in the presence of 10 mol % base. In Method A, transfer hydrogenation of acetophenone was performed at 100 °C using 2 mol % ruthenium catalyst ( 1 ) and methanol as the hydrogen source as well as the solvent.…”

Section: Resultsmentioning

confidence: 99%

Transfer Hydrogenation of Aldehydes and Ketones in Air with Methanol and Ethanol by an Air-Stable Ruthenium–Triazole Complex

Ghosh

Jana

Panda

et al. 2021

ACS Sustainable Chem. Eng.

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Coordination of 1,4-disubstituted 1,2,3-triazoles L 1 and L 2 with [(p-cymene)RuCl2]2 followed by dehydrochlorination in the presence of a base resulted in the formation of complexes 1 and 2, respectively. Both were tested for the transfer hydrogenation of aldehydes and ketones in air using ecologically benign and cheap ethanol as the hydrogen source in the presence of a catalytic amount of a base. Air-stable complex 1 was proved to be an active catalyst for the transfer hydrogenation of a wide variety of aromatic and aliphatic aldehydes and ketones bearing various functionalities. Catalyst 1 was also effective for the transfer hydrogenation of carbonyls using the simplest primary alcohol, methanol, under aerobic conditions. Under the present catalytic protocol, labile or reducible functionalities such as nitro, cyano, and ester groups were tolerated. Good selectivity was also observed for acyclic α,β-unsaturated carbonyls. However, this catalytic protocol was not selective for 2-cyclohexen-1-one as both alkene and keto moieties were reduced. The transfer hydrogenations are believed to proceed via a ruthenium-hydride intermediate. Finally, transfer hydrogenation of acetophenone using isopropanol as a commonly used hydrogen source was also performed and the sustainable and green credentials of these catalytic protocols utilizing methanol, ethanol, and isopropanol were compared with the help of the CHEM21 green metrics toolkit.

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Section: Resultsmentioning

confidence: 99%

Transfer Hydrogenation of Aldehydes and Ketones in Air with Methanol and Ethanol by an Air-Stable Ruthenium–Triazole Complex

Ghosh

Jana

Panda

et al. 2021

ACS Sustainable Chem. Eng.

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“…We evaluated the six catalytic protocols with the CHEM21 green metrics toolkit established by Clark et al 70 This CHEM21 green metrics toolkit is a quantitative extension of "The 12 Principles of Green Chemistry" and various synthetic chemical processes were evaluated with CHEM21 green metrics toolkit. [120][121][122][123][124][125] All these show that aerobic oxidations were performed at ambient conditions except Method E, which was carried out at 70 °C. Methods B, D, and E were performed in the presence of 3 mol% of 2b and 10 mol% of the TEMPO radical.…”

Section: Resultsmentioning

confidence: 98%

Aerobic oxidation of vanillyl alcohol to vanillin catalyzed by air-stable and recyclable copper complex and TEMPO under base-free conditions

Jana¹,

Sethi²,

Saha³

et al. 2022

Green Chem.

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“…An example of good practice is given in Scheme 2 and described below for a gas-liquid Ru-catalyzed ester hydrogenation continuous flow setup, which we recently reported in Green Chemistry. [30] Within the continuous flow setup, the two liquid feeds were introduced with high performance liquid chromatography (HPLC, Uniqsis) pumps. Hydrogen gas was introduced from a gas cylinder by using a calibrated mass flow controller (MFC, Bronkhorst EL-FLOW).…”

Section: Continuous Flow Configurationmentioning

confidence: 99%

Towards the Standardization of Flow Chemistry Protocols for Organic Reactions

Hone

Kappe

2021

Chemistry Methods

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Flow chemistry studies can sometimes be difficult to reproduce. In this article we provide guidance to scientists for experimental details that should be considered as part of any organic chemistry-based continuous flow study. A focus is placed on information that should be provided within reported studies to enable experiments to be more easily and reliably reproduced. Topics covered include flow reactor components and assembly, important parameter effects and useful performance criteria. The article covers aspects of homogeneous systems, multiphase transformations, and catalytic reactions (homogeneous and heterogeneous). A more detailed discussion of photochemistry, biocatalysis and electrochemical flow systems is outside the scope of this review.

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Optimization and sustainability assessment of a continuous flow Ru-catalyzed ester hydrogenation for an important precursor of a β2-adrenergic receptor agonist

Abstract: The development of a ruthenium-catalyzed continuous flow ester hydrogenation using hydrogen (H2) gas is reported. The reaction was utilized for the reduction of an important precursor in the synthesis of...

Cited by 18 publications

References 62 publications

Transfer Hydrogenation of Aldehydes and Ketones in Air with Methanol and Ethanol by an Air-Stable Ruthenium–Triazole Complex

Transfer Hydrogenation of Aldehydes and Ketones in Air with Methanol and Ethanol by an Air-Stable Ruthenium–Triazole Complex

Aerobic oxidation of vanillyl alcohol to vanillin catalyzed by air-stable and recyclable copper complex and TEMPO under base-free conditions

Towards the Standardization of Flow Chemistry Protocols for Organic Reactions

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