Base-Catalyzed Hydrogen Exchange

Elvidge, J. A.; Jones, John R.; O'Brien, Conor; Evans, E. A.; Sheppard, Hilary C.

doi:10.1016/s0065-2725(08)60458-4

Cited by 43 publications

(9 citation statements)

References 69 publications

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“…thiazole by one or more nitrogen atoms increased the exchange rate by a factor of lo4. And while the order of exchange rates was thiazole > oxazole > imidazole in the base-catalvzed process (17), the condensed ring derivatives showed a reversal, benzoxazole being deuterated 30 times faster than benzothiazole (1 8).…”

Section: Methods Of Pk Measurementmentioning

confidence: 98%

Acidity measurements in THF. V. Heteroaromatic compounds containing 5-membered rings

Fraser¹,

Mansour²,

Savard³

1985

Can. J. Chem.

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The pKa's of 13 heterocyclic aromatic compounds have been measured in tetrahydrofuran (THF) using 13C nmr spectroscopy. The acidifying effect of a nitrogen heteroatom is seen to be quite large (4–6 pK units versus C—H) on an adjacent C—H bond but small on a more remote hydrogen. Most of these aromatic heterocycles are sufficiently acidic, pKa < 34, to be completely deprotonated by lithium tetramethylpiperidide in THF. Benzoxazole appears to be an extremely strong carbon acid, its ring-opened isomer having a pKa of less than 15.7.

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Section: Methods Of Pk Measurementmentioning

confidence: 98%

Acidity measurements in THF. V. Heteroaromatic compounds containing 5-membered rings

Fraser¹,

Mansour²,

Savard³

1985

Can. J. Chem.

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show abstract

“…Ethanol (5 ml) was added and the reaction was heated at 781C for 24 h before being cooled to RT. TLC analysis (5:95 7 M methanolic ammonia : methylene chloride; R f [3-amino-4-ethylpyrazole] = 0.45; R f [4] = baseline) indicated the reaction was complete. Hydrochloric acid (12 M, 2.7 ml) was added and the reaction was stirred for 10 min and evaporated to give compound 4 plus salts (4.82 g).…”

Section: Synthesis Of [ 3 H]sch 727965 (2)mentioning

confidence: 99%

“…The placement of tritium in the 2-and 6-positions of the pyridine N-oxide is supported by work discussed in a review of base-catalyzed exchange on heterocyclic compounds. 4 Carbon-13-labeled Sch 727965 was prepared for use as a standard in a mass spectrometry based bioanalytical assay. The synthesis, summarized in Scheme 2, was based on the route that was developed and optimized by Medicinal 3,5,6 and Process…”

Section: -[ 14 C]-57-dichloro-3-ethyl-pyrazolo[15-a]pyrimidine (11)mentioning

confidence: 99%

Synthesis of ³H‐, ¹³C₃‐, and ¹⁴C‐labeled Sch 727965

Lavey

Hesk

Koharski

et al. 2010

Labelled Comp Radiopharmac

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“…Base-catalyzed exchange labeling of heterocyclic compounds has been reviewed 54 . A thorough discussion of deuterium labeling of such classes is available in A. F. Thomas's excellent book 53 ; many of the procedures described therein have been modified for tritium labeling.…”

Section: Thermodynamic Controlmentioning

confidence: 99%