3HNAAG, N‐acetyl‐l‐aspartyl‐l‐glutamic acid, has been widely used as a substrate in glutamate carboxypeptidase II (GCPII) reactions, either to determine the inhibitory constants at 50% inhibition ...(IC50) of novel compounds or to measure GCPII activities in different tissues harvested from various disease models. The importance of 3HNAAG, combined with its current commercial unavailability, prompted the development of a reliable eight‐step synthetic procedure towards 3H2NAAG starting from commercially available pyroglutamate. Pure 3HNAAG of high molar activity (49.8 Ci/mmol) and desired stereochemistry was isolated in high radiochemical yield (67 mCi) and radiochemical purity (>99%). The identity was confirmed by mass spectrometry and co‐injection with unlabeled reference.
3HNAAG, N‐acetyl‐l‐aspartyl‐l‐glutamic acid, widely used as a substrate in glutamate carboxypeptidase II (GCPII) reactions and no longer commercially available, was prepared by a reliable eight‐step synthetic procedure starting from commercially available pyroglutamate. Pure 3HNAAG of high molar activity (49.8 Ci/mmol) and desired optical configuration was isolated in high radiochemical yield (67 mCi) and radiochemical purity (>99%).
Direct Multi‐Deuterium Labelling of Pirtobrutinib Kriegelstein, Michal; Hojcsková, Jana; Hroch, Miloš ...
Journal of labelled compounds & radiopharmaceuticals,
July 2024, 2024-07-00, 20240701, Letnik:
67, Številka:
9
Journal Article
Recenzirano
ABSTRACT
Herein, we demonstrate an efficient method for multi‐deuterium labelling of pirtobrutinib—a Bruton's tyrosine kinase inhibitor recently approved by the FDA—using a straightforward hydrogen ...isotope exchange (HIE) reaction. A remarkably high level of deuterium incorporation was achieved using an excess of a Kerr‐type iridium catalyst. The key factor in the significant deuterium labelling was the decision to employ a deuterium uniformly labelled solvent, chlorobenzene‐d5, at an elevated temperature. Virtually, no d0–d3 species were detected, with only traces of d4–d5 isotopomers (< 5%) observable in the mass spectrum of pirtobrutinib‐d8, fulfilling requirements for stable isotope‐labelled internal standard. The labelled compound—mainly consisting of isotopomers d6–d9 at 82.4% of the total abundance—was isolated in a high yield (73%) and purity (99%). Noteworthy, fluorine group acting as a directing group was observed for the first time. Significant incorporation of deuterium in ortho‐positions, exceeding 87%, was observed. Interestingly, chlorinated solvent used in the HIE reactions was non‐specifically deuterated yielding up to 0.42 deuterium per chlorobenzene molecule even at an exceptionally low iridium catalyst loading of 4.17 × 10–2 mol%.
We present an efficient method for multi‐deuterium labelling of pirtobrutinib—a BTK inhibitor recently approved by the FDA—using a straightforward hydrogen isotope exchange (HIE) reaction. The use of a deuterium‐labelled solvent of chlorobenzene‐d5 at elevated temperatures resulted in a high degree of deuterium labelling, mainly pirtobrutinib‐d8. Our results show that the fluorine moiety can act as a potent ortho‐directing group, selectively moderating HIE reactions in the aromatic system under specific conditions. We also observed significant deuterium labelling of the chlorobenzene solvent during the HIE reactions.
At present, therapeutic drug monitoring is the standard in pharmacotherapy using medications with a narrow therapeutic index or showing serious adverse effects, such as in the case of ibrutinib. A ...technique commonly used for this purpose is liquid chromatography-tandem mass spectrometry combined with isotope dilution in sample processing. Although this method provides a high degree of reliability, its use can be complicated with some specific factors and does not guarantee trouble-free analysis. This paper is focused on investigating issues related to the differential adsorption of ibrutinib and its D4, D5 and 13C6 isotopically labeled analogues combined with instrument-specific carry-over. The results of the research point out the significantly different adsorption behavior of ibrutinib in fluidics of LC-MS compared with that of its D4, D5 and 13C6 stable isotope labeled analogues, showing preferential adsorption of non-labeled compound. The investigation also pointed to a strong affinity of ibrutinib to polymeric surfaces under specific conditions, which has to be taken into consideration during sample preparation and analysis. Our work opens a new field for the discussion of scarcely reported problem related to the use of stable isotope labeled internal standards in LC-MS/MS analysis.
•Ibrutinib and its D4, D5, 13C6 analogues show differential adsorption in LC/MS.•Differential adsorption is novel issue in use of isotope labeled internal standards.•The problem of differential adsorption is instrument-specific.•Ibrutinib strongly adsorbs to polymeric surfaces.
The synthesis of tritium-labelled glycine transporter 1 inhibitor Org24598 is reported. Because of the instability of the Org24598 skeleton under hydrogenation conditions, a synthetic approach using ...an in-house prepared tritium-labelled alkylating agent (
HMeI, SA = 26.2 Ci/mmol) was employed. Alternative methods of labelling are discussed.
Axially chiral trifluoromethylbenzimidazolylbenzoic acid (TBBA) was used as a chiral derivatization agent for the assignment of the absolute configuration of β-chiral primary alcohols. The structures ...varied from simple aliphatic alcohols to complex cyclic systems and highly substituted sugar derivatives. The NMR-based method was successfully implemented to evaluate 17 compounds and displayed Δδ
values higher than 0.1 ppm in most cases, which makes TBBA superior to MTPA and MPA and comparable to 9-AMA.
Synthesis of [13C6]‐ibrutinib Kriegelstein, Michal; Hroch, Miloš; Marek, Aleš
Journal of labelled compounds & radiopharmaceuticals,
November 2021, 2021-11-00, 20211101, Letnik:
64, Številka:
13
Journal Article
Recenzirano
Convenient and straightforward synthesis of ibrutinib labeled by carbon‐13 isotope is reported. Isotopically labeled building block is introduced in the last step of reaction sequence affording ...sufficient isolated yield (7%) of 13C6‐ibrutinib calculated towards starting commercially available 13C6‐bromobenzene.
Convenient and straightforward synthesis of 13C6‐ibrutinib is reported.
Racemic 2-(2-trifluoromethyl)-1H-benzodimidazol-1-yl)benzoic acid (TBBA) was synthesized in three steps from 1-fluoro-2-nitrobenzene. Target (P)- and (M)-TBBA atropisomers were stable with a ...racemization barrier above 30 kcal/mol. As a chiral derivatizing agent, TBBA showed much higher differences in chemical shifts (ΔδPM) than the conventional Mosher’s acid.
Axially chiral 2-(2-(trifluoromethyl)-1H-benzodimidazole-1-yl)benzoic acid (TBBA) was used as a chiral derivatizing agent to evaluate the limits of absolute configuration assignment for β-chiral ...aminoalcohols. Seven Boc-aminoalcohols and eight variously N-substituted (S)-phenylglycinols were prepared, and their TBBA esters were analyzed by NMR spectroscopy. Diverse substitution at the β-position was employed to demonstrate the effect of structure on the general conformational model and reliability of the absolute configuration assignment. It was concluded that hydrogen bond formation and steric hindrance were the main factors affecting the correct assignment for Boc-aminoalcohols.
