Synthesis and NMR Binding Studies towards Rational Design of a Series of Electron‐Withdrawing Diamide Receptors/Organocatalysts

Kinsella, Michael; Duggan, Patrick G.; Muldoon, Jimmy; Eccles, Kevin S.; Lawrence, Simon E.; Lennon, Claire M.

doi:10.1002/ejoc.201001439

Cited by 14 publications

(7 citation statements)

References 34 publications

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“…Next to the numerous urea and thiourea catalysts that have been reported, Lennon and co-workers took on the quest to evaluate a series of bisamides (e.g., 466) for Baylis−Hillman reactions (Scheme 59). 740 After testing the anion binding properties, the authors proposed that the increased reaction rates and yields could be assigned to the interaction of the anion receptors with the negatively charged intermediates in the reaction medium. Nagorny et al reported the first use of a three hydrogen-bond donor for anion binding catalysis.…”

Section: Organocatalysis Based On Interactions With Other Oxoanionsmentioning

confidence: 99%

Applications of Supramolecular Anion Recognition

et al. 2015

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Section: Organocatalysis Based On Interactions With Other Oxoanionsmentioning

confidence: 99%

Applications of Supramolecular Anion Recognition

et al. 2015

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“…Soon, the stronger hydrogen-bonding interactions were established, leading to the usual downfield shift of NH signals at the latter titration process. The unusual chemical shift change of interacting protons within the receptor upon binding of an anion had also been reported previously by Lennon and Gale (48,49). As for the chemical shift changes of three CH protons in pyrrole rings, the through-bond propagation effect (promoted by hydrogen-bonding interactions between pyrrole NHs and F 2 ) increased the electron cloud density of pyrrole rings, resulting to the initial upfield shift of these protons.…”

Section: Supramolecular Chemistry 765mentioning

confidence: 63%

Selective recognition and discrimination of H₂PO₄⁻ and F⁻ based on a cleft-shaped anion receptor incorporating bisamide and bispyrrole groups

Zhou

Zheng

Bao

2014

Supramolecular Chemistry

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2014) Selective recognition and discrimination of H 2 PO 4 -and F -based on a cleft-shaped anion receptor incorporating bisamide and bispyrrole groups, Supramolecular Chemistry, 26:10-12, 761-768,A simple anion receptor incorporating bisamide and bispyrrole groups as recognition sites was synthesised, and its binding properties towards anions were studied by UV-vis, 1 H NMR, ESI-MS spectra and theoretical calculations. This receptor exhibited a selective complexation with biologically important H 2 PO 2 4 and F 2 over other anions tested in dry CH 3 CN. Significantly, the discrimination of these two anions could be realised via the obviously different UV-vis readouts of the receptor.

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“…In parallel to NMR binding studies, the p K a ’s of silanols and carbon analogues were calculated (see Supporting Information) and we observed the p K a of silanols were 3 to 4 p K a units lower than carbon analogues. The larger NMR shift of the SiOH relative to the carbon analogues and the p K a calculation results are attributed to enhanced hydrogen-bonding capabilities of the pyrrolidinylsilanol …”

Section: Nmr Studies Of Hydrogen Bondingmentioning

confidence: 89%

Enantiocontrol with a Hydrogen-bond Directing Pyrrolidinylsilanol Catalyst

2012

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Dichloromethane (DCM), hexane, ethyl acetate (EtOAc), and diethyl ether (Et 2 O) were obtained from EMD Chemicals. Toluene (PhMe), methanol (MeOH), and tetrahydrofuran (THF) were obtained from Fisher Scientific. Palladium on carbon (5 wt% and 10 wt%), anhydrous magnesium sulfate, (-)-sparteine, acetaldehyde, and 2-mesitylmagnesium bromide solution (1.0 M in Et 2 O) were acquired from Sigma Aldrich. Dimethoxyethane, trichlorosilane, secbutyllithium (1.3 M in cyclohexane/hexanes (98/2)), and ytterbium (III) triflate hydrate were purchased from Acros Organics.tert-butyl-1-pyrrolidine-carboxylate, ammonium hexafluorosilicate, amberlyst-A21, 1-methylisatin, and 1-phenylisatin were purchased from Alfa-Aesar. Diphenylchlorosilane was obtained from Gelest. 4-chloroisatin was obtained from TCI America. Commercially available reagents were purchased and used without further purification unless otherwise indicated. sec-Butyllithium was titrated before use with diphenylacetic acid to obtain accurate concentration for reactions.Reactions were analyzed by thin layer chromatography (TLC) on EMD glass plates that were pre-coated with silica gel 60 F254, and the reactions were purified by column chromatography using Acros silica gel 60 Å (0.035-0.070 mm) or Sigma Aldrich silica gel 150 Å grade 62 (60-200 mesh). The following abbreviations are used throughout: ethyl acetate (EtOAc), acetonitrile (MeCN), dichloromethane (DCM), isopropanol (IPA), methanol (MeOH), enantiomeric excess (ee), triethylamine (Et 3 N). All aldol reactions were performed in glass vials with Teflon caps and exposure to atmospheric conditions.All 1 H and 13 C NMR spectra were recorded at ambient temperature at 300, 400, and 600 MHz or 75, 100, and 150 MHz, respectively. 19 F NMR spectra were recorded at ambient temperature at 282 MHz. 29 Si NMR spectra were recorded at ambient temperature at 119 MHz. The 1 H spectral data are reported as follows: chemical shift in parts per million downfield from tetramethylsilane on the δ scale, multiplicity (s, singlet; d, doublet; t, triplet; q, quartet; s, septet; m, multiplet; dd, doublet of doublets, and b, broadened), coupling constant (Hz), and integration. Carbon NMR chemical shifts are reported in ppm from tetramethylsilane with the solvent reference employed as the internal standard (deuterochloroform (CDCl 3 )) at 77.16 ppm. Unless otherwise indicated, all chiral stationary phase HPLC analyses were performed with a Daicel CHIRALCEL OD-H column (4.6 x 250mm, 5 µm), CHIRALPAK AD-H column (4.6 x 250 mm, 5 µm), or CHIRALPAK AS-H column (4.6 x 250 mm, 5 µm), with corresponding guard columns, with a flow rate of 0.5 -1.0 mL/min (2-propanol/hexanes isocratic system) using a photodiode array detector and at various column oven temperature. Compounds were analyzed by HRMS on an orbitrap spectrometer using electrospray ionization in the positive ion mode at >60000 resolutions and using typical ESI source values. These settings result in mass accuracies <5 ppm. Some compounds were analyzed by LRMS in the positive ion mode o...

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Synthesis and NMR Binding Studies towards Rational Design of a Series of Electron‐Withdrawing Diamide Receptors/Organocatalysts

Cited by 14 publications

References 34 publications

Applications of Supramolecular Anion Recognition

Applications of Supramolecular Anion Recognition

Selective recognition and discrimination of H₂PO₄⁻ and F⁻ based on a cleft-shaped anion receptor incorporating bisamide and bispyrrole groups

Enantiocontrol with a Hydrogen-bond Directing Pyrrolidinylsilanol Catalyst

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Synthesis and NMR Binding Studies towards Rational Design of a Series of Electron‐Withdrawing Diamide Receptors/Organocatalysts

Cited by 14 publications

References 34 publications

Applications of Supramolecular Anion Recognition

Applications of Supramolecular Anion Recognition

Selective recognition and discrimination of H2PO4− and F− based on a cleft-shaped anion receptor incorporating bisamide and bispyrrole groups

Enantiocontrol with a Hydrogen-bond Directing Pyrrolidinylsilanol Catalyst

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Selective recognition and discrimination of H₂PO₄⁻ and F⁻ based on a cleft-shaped anion receptor incorporating bisamide and bispyrrole groups