Solution to NMR hide-and-seek challenge

Analytical and Bioanalytical Chemistry, Apr 2017

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Solution to NMR hide-and-seek challenge

Solution to NMR hide-and-seek challenge Reinhard Meusinger 0 0 Institute of Organic Chemistry and Biochemistry, University of Technology Darmstadt , Alarich-Weiss-Str. 4, 64287 Darmstadt , Germany Reinhard Meusinger Fig. 1 Histamine (C5H9N3, M = 111.15 g/mol). IUPAC name 2-(1Himidazol-4-yl)ethanamine - The substance described in the NMR hide-and-seek challenge [1] is histamine (Fig. 1). In the realm of natural products, histamine is one of the simplest nitrogen-containing compounds. The colourless hygroscopic crystals melt at 83.5 °C and are easily dissolved in water. In aqueous solution histamine exists in two tautomeric forms (Fig. 2). Histamine plays an important role in the human body: it is involved in several physiological functions as in immune responses and it acts as a neurotransmitter. The compound was synthesized first by Windaus and Vogt in 1907 via Curtius degradation of imidazole propionic acid hydrazide. They noted: “we have not yet fully investigated this peculiar substance. The investigation progresses slowly because of the difficult accessibility of the starting material. Nevertheless we report the previous results now, since others are working on the synthesis of histidine as well” [2]. Three years later Dale and Laidlaw [3] fully described many of the physiological effects of this substance.The name “histamine” was derived from “histo” and “amine”, yielding “tissue amine”. Occasionally in the medical literature the term “H substance” is used for histamine or a hypothetical histaminelike diffusible substance released in allergic reactions of skin and in the responses of tissue to inflammation. However, the histamine content of a single nettle hair was found to be only 6 ng [4]. For structural determination the 1H–13C heteronuclear multiple bond correlation spectrum is given with the complete assignment of all carbon and hydrogen atoms that are detectable in dimethyl-d6 sulfoxide solution of histamine dihydrochloride (Fig. 3). Fig. 2 The tautomeric forms of histamine Fig. 3 Heteronuclear multiple bond correlation spectrum of histamine [500 MHz, dimethyl-d6 sulfoxide (DMSO)]. The symmetrical satellite signals are residual single quantum coherence signals (so-called heteronuclear single quantum coherence artefacts) and are marked by X Meusinger R . Anal Bioanal Chem . 2016 ; 408 : 7537 - 41 . Windaus A , Vogt W . Ber Dtsch Chem Ges . 1907 ; 40 : 3691 - 5 . 3. Dale HH , Laidlaw PP. J Physiol . 1910 ; 41 : 318 - 44 . 4. Oliver F , Amon EU , Breathnach A , Francis DM , Sarathchandra P , Black AK , et al. Clin Exp Dermatol . 1991 ; 16 : 1 - 7 .

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Solution to NMR hide-and-seek challenge, Analytical and Bioanalytical Chemistry, 2017, 2499-2500, DOI: 10.1007/s00216-016-0177-6