A strategy for evaluation of isotopic enrichment and structural integrity of deuterium labelled compounds by using HR-MS and NMR.

Determining the purity of deuterium labelled compounds is important due to the increasing use of these compounds in mass spectrometry (MS) based quantitative analyses for targeting metabolic flux, reducing toxicity, confirming reaction mechanisms during synthesis, predicting enzyme mechanisms, and enhancing the efficacy of drugs, in quantitative proteomics, and also as internal standards. In the present study, a strategy using liquid chromatography electrospray ionization high resolution mass spectrometry (LC-ESI-HR-MS) and nuclear magnetic resonance (NMR) spectroscopy was proposed to determine the isotopic enrichment and structural integrity of deuterium labelled compounds. The proposed strategy involves recording full scan MS, extracting and integrating isotopic ions, and calculating the isotopic enrichment of the desired labelled compounds. NMR analysis confirms structural integrity or positions of labelled atoms and can provide insights into the relative percent isotopic purity. This strategy was used to evaluate the isotopic enrichment and structural integrity of in-house synthesized compounds as well as a series of commercially available deuterium labelled compounds. The % isotopic purity for labelled compounds of a benzofuranone derivative (BEN-d2), tamsulosin-d4 (TAM-d4), oxybutynin-d5 (OXY-d5), eplerenone-d3 (EPL-d3), and propafenone-d7 (PRO-d7) was calculated and found to be 94.7, 99.5, 98.8, 99.9, and 96.5, respectively. All the samples were run in triplicate and the results were observed to be reproducible.

Organocatalytic, highly enantioselective vinylogous Mukaiyama-Michael reaction of acyclic dienol silyl ethers.

Now also acyclic: The first catalytic, enantioselective, vinylogous Michael reaction of linear, acyclic dienol silyl ethers was achieved. The reaction, based upon the principle of iminium ion catalysis, delivered 1,7-dioxo compounds in one step with good yields, complete regio-, and excellent enantioselectivity. γ-Substituted dienol silyl ethers furnished products with two new stereogenic centers with good diastereoselectivity. Ms = mesityl, PNBA = para-nitrobenzoic acid.

10 years of click chemistry: synthesis and applications of ferrocene-derived triazoles.

Click chemistry has played a significant role as a rapid and versatile strategy for conjugating two molecular fragments under very mild reaction conditions. Introduction of ferrocene-derived triazole systems using click chemistry has attracted enormous interest in various fields due to its potential applications in electrochemical techniques for detection and sensing. The present discussion focuses on the synthesis of ferrocene-triazole and the importance of using a CuAAC reaction for such conjugation. Applications of ferrocene-based click reactions in conjugate chemistry, asymmetric catalysis, medicinal chemistry, host-guest interactions, and materials chemistry have been highlighted.