Stereochemistry of reductive dehalogenation with deuterium gas

Kaspersen, Frans M.; Sperling, Eric M. G.

doi:10.1002/jlcr.2580230605

Cited by 1 publication

(2 citation statements)

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“…Hundreds of tritiated compounds have been prepared by this approach. 19,20 Moreover, the corresponding deuterium labelling procedure has also been utilised for many years, [21][22][23] either using conventional hydrogenation with deuterium gas or by transfer-hydrogenation with various deuterium donors. 24,25 The dehalogenation of chloroaromatics, however, generally gives low atom% abundance 26 due to competing isotopic scrambling reactions which introduce protium instead of deuterium or tritium at the labelling site.…”

Section: Introductionmentioning

confidence: 99%

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Studies of hydrogen isotope scrambling during the dehalogenation of aromatic chloro‐compounds with deuterium gas over palladium catalysts

Lockley

Venanzi

Crane

2020

Labelled Comp Radiopharmac

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Catalytic dehalogenation of aromatic halides using isotopic hydrogen gas is an important strategy for labelling pharmaceuticals, biochemicals, environmental agents and so forth. To extend, improve and further understand this process, studies have been carried out on the scrambling of deuterium isotope with protium during the catalytic deuterodehalogenation of model aryl chlorides using deuterium gas and a palladium on carbon catalyst in tetrahydrofuran solution. The degree of scrambling was greatest with electron‐rich chloroarene rings. The tetrahydrofuran solvent and the triethylamine base were not the source of the undesired protium; instead, it arose, substantially, from the water content of the catalyst, though other sources of protium may also be present on the catalyst. Replacement of the Pd/C catalyst with one prepared in situ by reduction of palladium trifluoroacetate with deuterium gas and dispersed upon micronised polytetrafluoroethylene led to much reduced scrambling (typically 0–6% compared with up to 40% for palladium on carbon) and to high atom% abundance, regiospecific labelling. The improved catalytic system now enables efficient polydeuteration via the dehalogenation of polyhalogenated precursors, making the procedure viable for the preparation of MS internal standards and, potentially, for high specific activity tritium labelling.

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Section: Introductionmentioning

confidence: 99%

“…Hundreds of tritiated compounds have been prepared by this approach 19,20 . Moreover, the corresponding deuterium labelling procedure has also been utilised for many years, 21–23 either using conventional hydrogenation with deuterium gas or by transfer‐hydrogenation with various deuterium donors 24,25 …”

Section: Introductionmentioning

confidence: 99%