Synthesis of ether lipids: natural compounds and analogues

• Marco Antônio G. B. Gomes,
• Alicia Bauduin,
• Chloé Le Roux,
• Romain Fouinneteau,
• Wilfried Berthe,
• Mathieu Berchel,
• Hélène Couthon and
• Paul-Alain Jaffrès

Beilstein J. Org. Chem. 2023, 19, 1299–1369, doi:10.3762/bjoc.19.96

Light-responsive rotaxane-based materials: inducing motion in the solid state

• Adrian Saura-Sanmartin

Beilstein J. Org. Chem. 2023, 19, 873–880, doi:10.3762/bjoc.19.64

• UMUMOF-(E)-3 due to the decrease of the number of hydrogen bonds interactions between the counterparts, as determined by solid-state 2H NMR. Interestingly, UMUMOF-(E)-3 was employed as a molecular nanodispenser of para-benzoquinone working through a cyclic operation mode which involved three steps

Chlorination of phenylallene derivatives with 1-chloro-1,2-benziodoxol-3-one: synthesis of vicinal-dichlorides and chlorodienes

• Zhensheng Zhao and
• Graham K. Murphy

Beilstein J. Org. Chem. 2018, 14, 796–802, doi:10.3762/bjoc.14.67

• scrambling observable by 1H or 2H NMR of the product mixture, it appeared that 1,2-phenyl shifts or other rearrangement processes were not involved in the reaction. A further reaction was carried out in the presence of the radical scavenger TEMPO (1.5 equiv), from which only a trace of 3b was recovered

Stereochemical outcomes of C–F activation reactions of benzyl fluoride

• Neil S. Keddie,
• Pier Alexandre Champagne,
• Justine Desroches,
• Jean-François Paquin and
• David O'Hagan

Beilstein J. Org. Chem. 2018, 14, 106–113, doi:10.3762/bjoc.14.6

• an enantiopure isotopomer of benzyl fluoride to identify whether the reaction conditions favour a dissociative (SN1) or associative (SN2) pathway. [2H]-Isotopomer ratios in the reactions were assayed using the Courtieu 2H NMR method in a chiral liquid crystal (poly-γ-benzyl-L-glutamate) matrix and

• demonstrated that both associative and dissociative pathways operate to varying degrees, according to the nature of the nucleophile and the hydrogen bond donor. Keywords: benzylic fluorides; C–F activation; chiral liquid crystal; 2H NMR; PBLG; stereochemistry; Introduction The C–F bond is the strongest

• stereointegrity can be determined by examining the enantiopurity of the isotopically labelled product. Quadrupolar 2H-nuclei can serve as a particularly useful NMR probe for assaying enantiopurity. If the 2H NMR is recorded in a lyotropic liquid crystalline solvent, where tumbling of the solute is restricted

Membrane properties of hydroxycholesterols related to the brain cholesterol metabolism

• Malte Hilsch,
• Ivan Haralampiev,
• Peter Müller,
• Daniel Huster and
• Holger A. Scheidt

Beilstein J. Org. Chem. 2017, 13, 720–727, doi:10.3762/bjoc.13.71

• of several hydroxycholesterols with those of cholesterol using 2H NMR spectroscopy, a membrane permeability assay, and fluorescence microscopy experiments. It is shown that hydroxycholesterols do not exert the unique impact on membrane properties characteristic for cholesterol with regard to the

• 2H NMR measurements, only a very small increase of acyl chain order was observed in the presence of 24S-HC [8]. Surprisingly, in the same study, 24S-HC and 27-HC exhibited a comparable effect on the acyl chain order compared to endogenous cholesterol measuring the diphenylhexatriene (DPH) anisotropy

• chain order of hydroxycholesterol-containing membranes The influence of the hydroxycholesterols on the lipid chain order and the degree of lipid condensation was investigated by 2H NMR measurements on lipid membranes of chain deuterated 1-palmitoyl-d31-2-oleoyl-sn-glycero-3-phosphocholine (POPC-d31) in

Biosynthetic origin of butyrolactol A, an antifungal polyketide produced by a marine-derived Streptomyces

• Enjuro Harunari,
• Hisayuki Komaki and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2017, 13, 441–450, doi:10.3762/bjoc.13.47

• purchased from Sigma-Aldrich Co. LLC. 1H and 13C NMR spectra were obtained on a Bruker AVANCE 500 spectrometer in DMSO-d6 using the signal of the residual solvent signals (δH 2.50, δC 40.0) as an internal standard. The 2H NMR spectrum was obtained on a Bruker AVANCE 500 spectrometer in DMSO. Chemical shifts

• ; pink, PKS for polyketide backbone of 1; yellow, genes for biosynthesis of hydroxymalonyl-ACP; gray, transporter. Biosynthetic pathway of hydroxymalonyl-ACP. Adapted from [24]. Incorporation of L-valine-d8 into 1. (a) 1H NMR spectrum of natural 1 and 2H NMR spectrum of L-valine-d8-labeled 1. (b) ESIMS

Polyketide stereocontrol: a study in chemical biology

• Kira J. Weissman

Beilstein J. Org. Chem. 2017, 13, 348–371, doi:10.3762/bjoc.13.39

• erythromycin producer Saccharopolyspora erythraea, leading to the generation of isotopically-labeled (2R)- and (2S)-methylmalonyl-CoA in situ [23]. When a precursor of (2S)-methylmalonyl-CoA, [2-2H2,2-13C]propionate, was used, analysis of the products by difference 13C{1H,2H} NMR provided evidence for isotopic

[²H₂₆]-1-epi-Cubenol, a completely deuterated natural product from Streptomyces griseus

• Christian A. Citron and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2013, 9, 2841–2845, doi:10.3762/bjoc.9.319

• [15], allowing for a detailed interpretation of the mass spectrum of a deuterated analyte. A drawback is that high incorporation rates are required to investigate the site of incorporation by 1H NMR spectroscopy, but 2H NMR spectroscopy offers a suitable alternative [16][17]. Furthermore, deuterium

Intramolecular carbolithiation cascades as a route to a highly strained carbocyclic framework: competition between 5-exo-trig ring closure and proton transfer

• William F. Bailey and
• Justin D. Fair

Beilstein J. Org. Chem. 2013, 9, 537–543, doi:10.3762/bjoc.9.59

• % isolated yield. Quenching with MeOD afforded an authentic sample of 4 deuterated at the C(2) position (2H NMR: δ 5.84–5.75 (m, 1D)); the lack of a molecular ion in the GC–MS of triene 4 precluded accurate determination of the deuterium content. Addition at –78 °C of dry, oxygen-free N,N,N’,N

Use of mixed Li/K metal TMP amide (LiNK chemistry) for the synthesis of [2.2]metacyclophanes

• Marco Blangetti,
• Patricia Fleming and
• Donal F. O'Shea

Beilstein J. Org. Chem. 2011, 7, 1249–1254, doi:10.3762/bjoc.7.145

• selective site of metalation should be the more acidic 2-methyl position [26]. This was confirmed by 2H NMR, which showed that incorporated deuterium was above 90% in the 2-methyl position with less than 10% in the 4-methyl group and no detectable aryl deuteration (Figure 2). A similar experiment was

• deuteration gave the di-deuterated product D2-6f. 2H NMR analysis showed no aryl or bridging methylene deuteration, with deuterium incorporated only into the two non-equivalent benzylic methyl positions (Figure 3). With the benzylic metalation confirmed, the second step to complete the [2.2]metacyclophane

• reported in due course. Additional synthetic applications of LiNK metalation conditions are also under development. Xylene substrates. Metalation selectivity for 4e (arrows indicate potential metalation sites). 2H NMR spectrum in CH2Cl2. *CD2Cl2. **2-Methyl-4-D-methylbenzoic acid. Di-metalation selectivity

Low temperature enantiotropic nematic phases from V-shaped, shape-persistent molecules

• Matthias Lehmann and
• Jens Seltmann

Beilstein J. Org. Chem. 2009, 5, No. 73, doi:10.3762/bjoc.5.73

• molecules with rigorously defined shape (bending angle) for the formation of the desired phase [5][7]. But it was not until 2004 that sufficient evidence was presented for biaxiality of nematic phases in the series of V-shaped oxadiazoles by X-ray diffraction and solid-state 2H NMR spectroscopy [8][9][10