Microwave-assisted synthesis of (RS) methyl-2-([2′-14C]4,6-dimethoxypyrimidin-2′-yloxy)-2-phenyl [1-14C]ethanoate

Mathew, Kiran; Ravi, S.; Unny, V. K. P.; Sivaprasad, N.

doi:10.1002/jlcr.1078

Cited by 4 publications

(6 citation statements)

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“…The following chemicals were purchased from commercial suppliers and used as received: 2-propanol- d 0 (Sigma-Aldrich, 99.5% anhydrous), 2-propanol- d 8 (Sigma-Aldrich, 99%, 99.5 atom % D), phenyl isopropyl ether (P i PE, Enamine, 95%), ethylene glycol (Mallinckrodt), and lead nitrate (Sigma-Aldrich). Selectively 13 C-labeled benzyl phenyl ether was synthesized from toluene-α- 13 C and phenol-1- 13 C (Cambridge Isotopes, 98%, 99 atom % 13 C) according to literature procedures. , The 2 wt % Ni/γ-Al 2 O 3 catalyst was prepared using a modified literature procedure …”

Section: Experimental Methodsmentioning

confidence: 99%

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Operando MAS NMR Reaction Studies at High Temperatures and Pressures

Walter

Qi²,

Chamas³

et al. 2018

J. Phys. Chem. C

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Operando MAS NMR studies provide unique insights into the details of chemical reactions; comprehensive information about temperature-and time-dependent changes in chemical species is accompanied by similarly rich information about changes in phase and chemical environment. Here we describe a new MAS NMR rotor (the WHiMS rotor) capable of achieving internal pressures up to 400 bar at 20 °C or 225 bar at 250 °C, a range that includes many reactions of interest. The MAS NMR spectroscopy enabled by these rotors is ideal for studying the behavior of mixed-phase systems, such as reactions involving solid catalysts and volatile liquids, with the potential to add gases at high pressure. The versatile operation of the new rotors is demonstrated by collecting operando 1 H and 13 C spectra during the hydrogenolysis of benzyl phenyl ether, catalyzed by Ni/γ-Al 2 O 3 at ca. 250 °C, both with and without H 2 (g) supplied to the rotor. The 2-propanol solvent, which exists in the supercritical phase under these reaction conditions, serves as an internal source of H 2 . The NMR spectra provide detailed kinetic profiles for the formation of the primary products toluene and phenol as well as secondary hydrogenation and etherification products.

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Section: Experimental Methodsmentioning

confidence: 99%

“…Selectively 13 C-labeled benzyl phenyl ether was synthesized from toluene-α- 13 C and phenol-1-13 C (Cambridge Isotopes, 98%, 99 atom % 13 C) according to literature procedures. 30,31 The 2 wt % Ni/γ-Al 2 O 3 catalyst was prepared using a modified literature procedure. 32 Operando Solid-State NMR.…”

Section: ■ Introductionmentioning

confidence: 99%

Operando MAS NMR Reaction Studies at High Temperatures and Pressures

Walter

Qi²,

Chamas³

et al. 2018

J. Phys. Chem. C

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“…13 C-labelled benzyl bromide was prepared following a modified literature procedure. 71 Toluene--13 C (100 mg, 1.07 mmol) was stirred with MnO 2 (93 mg, 1.07 mmol) and Br 2 (60 µL, 1.17 mmol) in CH 2 Cl 2 (10 mL) for 1 h in a roundbottom flask (100 mL) until the solution became colorless.…”

Section: Synthesis Of 13 C-labelled Benzyl Phenyl Ether (Bpe)mentioning

confidence: 99%

Unraveling the Dynamic Network in the Reactions of an Alkyl Aryl Ether Catalyzed by Ni/γ-Al₂O₃ in 2-Propanol

Chamas

Jones

et al. 2019

J. Am. Chem. Soc.

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The reductive cleavage of aryl ether linkages is a key step in the disassembly of lignin to its monolignol components, where selectivity is determined by the kinetics of multiple parallel and consecutive liquidphase reactions. Triphasic hydrogenolysis of 13C-labeled benzyl phenyl ether (BPE, a model compound for the major β-O-4 linkage in lignin), catalyzed by Ni/γ-Al2O3, was observed directly at elevated temperatures (150-175 °C) and pressures (79-89 bar) using operando magic-angle spinning NMR spectroscopy. Liquid-vapor partitioning in the NMR rotor was quantified using the 13C NMR resonances for the 2-propanol solvent, whose chemical shifts report on the internal reactor temperature. At 170 °C, BPE is converted to toluene and phenol with k1 = 0.17 s-1 gcat-1 and an apparent activation barrier of (80 ± 8) kJ mol-1. Subsequent phenol hydrogenation occurs much more slowly (k2 = 0.0052 s-1 gcat-1 at 170-175 °C), such that cyclohexanol formation is significant only at higher temperatures. Toluene is stable under these reaction conditions, but its methyl group undergoes facile H/D exchange (k3 = 0.046 s-1 gcat-1 at 175 °C). While the source of the reducing equivalents for both hydrogenolysis and hydrogenation is exclusively H2/D2(g) rather than the alcohol solvent at these temperatures, the initial isotopic composition of adsorbed H/D on the catalyst surface is principally determined by the solvent isotopic composition (2-PrOH/D). All reactions are preceded by a pronounced induction period associated with catalyst activation. In air, Ni nanoparticles are passivated by a surface oxide monolayer, whose removal under H2 proceeds with an apparent activation barrier of (72 ± 13) kJ mol-1. The operando NMR spectra provide molecularly specific, time-resolved information about the multiple simultaneous and sequential processes as they occur at the solid-liquid interface.

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“…Our preparation of carbon‐14–labeled racemic tropic acid provides access to both enantiomers of Buscopan, and a viable method of separating the enantiomers of tropic acid is developed. The synthesis of racemic tropic acid (Scheme ) started from benzyl bromide, which was converted to the nitrile ( 2 ) in water in the presence of potassium cyanide‐ 14 C and tetrabutylammonium bromide . Hydrolysis of the nitrile group to ( 3 ) and esterification in ethanol afforded phenylacetic acid ethyl ester ( 4 ) in excellent yield.…”

Section: Resultsmentioning

confidence: 99%

“…The synthesis of racemic tropic acid (Scheme 2) started from benzyl bromide, which was converted to the nitrile (2) in water in the presence of potassium cyanide-14 C and tetrabutylammonium bromide. 21,22 Hydrolysis of the nitrile group to (3) and esterification in ethanol afforded phenylacetic acid ethyl ester (4) in excellent yield. The phenyl ethyl acetate (4) was then reacted with ethyl formate and sodium hydride to furnish 3-hydroxy-2-phenyl-acrylic acid ethyl ester (5).…”

Section: Resultsmentioning

confidence: 99%

Buscopan labeled with carbon‐14 and deuterium

Latli

Stiasni

Hrapchak

et al. 2016

Labelled Comp Radiopharmac

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Hyosine butyl bromide, the active ingredient in Buscopan, is an anticholinergic and antimuscarinic drug used to treat pain and discomfort caused by abdominal cramps. A straightforward synthesis of carbon-14- and deuterium-labeled Buscopan was developed using scopolamine, n-butyl-1- C bromide, and n-butyl- H bromide, respectively. In a second carbon-14 synthesis, the radioactive carbon was incorporated in the tropic acid moiety to follow its metabolism. Herein, we describe the detailed preparations of carbon-14- and deuterium-labeled Buscopan.

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Microwave-assisted synthesis of (RS) methyl-2-([2′-14C]4,6-dimethoxypyrimidin-2′-yloxy)-2-phenyl [1-14C]ethanoate

Abstract: SummaryWe report here a facile synthesis of (14 C]ethanoate under microwave irradiation.

Cited by 4 publications

References 5 publications

Operando MAS NMR Reaction Studies at High Temperatures and Pressures

Operando MAS NMR Reaction Studies at High Temperatures and Pressures

Unraveling the Dynamic Network in the Reactions of an Alkyl Aryl Ether Catalyzed by Ni/γ-Al₂O₃ in 2-Propanol

Buscopan labeled with carbon‐14 and deuterium

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Microwave-assisted synthesis of (RS) methyl-2-([2′-14C]4,6-dimethoxypyrimidin-2′-yloxy)-2-phenyl [1-14C]ethanoate

Abstract: SummaryWe report here a facile synthesis of (14 C]ethanoate under microwave irradiation.

Cited by 4 publications

References 5 publications

Operando MAS NMR Reaction Studies at High Temperatures and Pressures

Operando MAS NMR Reaction Studies at High Temperatures and Pressures

Unraveling the Dynamic Network in the Reactions of an Alkyl Aryl Ether Catalyzed by Ni/γ-Al2O3 in 2-Propanol

Buscopan labeled with carbon‐14 and deuterium

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Product

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Unraveling the Dynamic Network in the Reactions of an Alkyl Aryl Ether Catalyzed by Ni/γ-Al₂O₃ in 2-Propanol