Synthesis and Resolution of the Atropisomeric 1,1'-Bi-2-naphthol: An Experiment in Organic Synthesis and 2-D NMR Spectroscopy

Mak, Kendrew Kin Wah

doi:10.1021/ed081p1636

Cited by 7 publications

(4 citation statements)

References 8 publications

(14 reference statements)

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“…3. The proton spectrum of BN in chloroform has been reported by Mak,10 and is qualitatively similar to the aqueous BN and BNDHP spectra shown here. The pair of doublets at ca 8 ppm is well resolved in chloroform and is also attributed to H-4 and H-5 by Mak.…”

Section: Resultssupporting

confidence: 87%

Proton NMR assignments for R,S‐1,1′‐binaphthol (BN) and R,S‐1,1′‐binaphthyl‐2,2′‐diyl hydrogen phosphate (BNDHP) interacting with bile salt micelles

Eckenroad

Thompson

Strein

et al. 2006

Magnetic Reson in Chemistry

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We report proton chemical shifts for two model chiral analytes that are commonly used in the study of micellar electrokinetic capillary chromatography (MEKC), R,S-1,1'-binaphthol (1, BN) and R,S-1,1'-binaphthyl-2,2'-diyl hydrogen phosphate (2, BNDHP), in the absence and presence of monomers and micelles of sodium cholate and sodium deoxycholate. The analytes undergo fast exchange in and out of the micelles, which perturbs the analytes' chemical shifts, and which we use to resolve some resonances that are degenerate at both 300 and 600 MHz. Although BN and BNDHP are simple molecules, the proton assignments are only unambiguously established with the aid of the exchange with micelles, an attractive alternative to other methodologies such as the use of paramagnetic shift reagents which may also cause spectral distortions. We rely also upon 2D-NOE spectra of samples in the presence of micelles to perform these assignments. Recently published assignments, which were based upon 2D-COSY spectroscopy, appear to be in error and are corrected here. Finally, we note that these shifts are information-rich reporters on the nature of the interactions of these model analytes with the micelles.

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Section: Resultssupporting

confidence: 87%

Proton NMR assignments for R,S‐1,1′‐binaphthol (BN) and R,S‐1,1′‐binaphthyl‐2,2′‐diyl hydrogen phosphate (BNDHP) interacting with bile salt micelles

Eckenroad

Thompson

Strein

et al. 2006

Magnetic Reson in Chemistry

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“…Confirmatory studies were carried out using DSC and NMR on products obtained from the reaction on a larger scale. Figure S2 shows the NMR spectrum of the binol product (the inset shows an expansion of the aromatic region) which is in good agreement with the literature [34].…”

Section: Scheme 1 Overall Synthesis Of Binol From 2-naphthol and Iron (Iii) Chloride Hexahydratesupporting

confidence: 88%

Hot-stage microscopy - Direct Analysis in Real-time mass spectrometry (HDM) as a novel tool for monitoring thermally-driven reactions on a small scale

Ashton

Harding

Midgley

et al. 2020

Analytica Chimica Acta

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There is a requirement for reliable real-time analytical tools for reaction monitoring to optimise chemical syntheses. We have developed a new technique which combines thermal analysis, digital microscopy and chemical identification using ambient ionisation mass spectrometry. We term this hot-stage microscopy-Direct Analysis in Real-Time mass spectrometry (HDM). The technique provides optical data as a function of temperature coupled with chemical characterisation of evolved species, including reactants, intermediates and products throughout the course of a reaction.In addition, only a few milligrams of sample are required with analyte detection down to the nanogram range. We demonstrate the benefits of HDM using a series of solventfree reactions. Our results confirm the suitability of the technique as the reactions studied follow the same pathways as published previously. The accurate temperature control achieved with HDM could also be used to assess the optimum temperature at which thermally-driven reactions can proceed efficiently.

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“…Finely grained chemical shift titration experiments were carried out by varying deoxycholate concentration in the presence of R- or S-BNDHP (2.5 mM) at basic pH (pH 12), and are summarized in Figure and further analyzed in Figures – (all presented later in this work). Chemical shifts follow prior assignments and the original spectra are provided in section S.3 in the Supporting Information. , From these 1D chemical shift data, the following discussion points arise.…”

Section: Resultsmentioning

confidence: 99%

“…Chemical shifts follow prior assignments and the original spectra are provided in section S.3 in the Supporting Information. 41,68 From these 1D chemical shift data, the following discussion points arise.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Stepwise Aggregation of Cholate and Deoxycholate Dictates the Formation and Loss of Surface-Available Chirally Selective Binding Sites

et al. 2018

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Bile salts are facially amphiphilic, naturally occurring chemicals that aggregate to perform numerous biochemical processes. Because of their unique intermolecular properties, bile salts have also been employed as functional materials in medicine and separation science (e.g., drug delivery, chiral solubilization, purification of single-walled carbon nanotubes). Bile micelle formation is structurally complex, and it remains a topic of considerable study. Here, the exposed functionalities on the surface of cholate and deoxycholate micelles are shown to vary from one another and with the micelle aggregation state. Collectively, data from NMR and capillary electrophoresis reveal preliminary, primary, and secondary stepwise aggregation of the salts of cholic (CA) and deoxycholic (DC) acid in basic conditions (pH 12, 298 K), and address how the surface availability of chirally selective binding sites is dependent on these sequential stages of aggregation. Prior work has demonstrated sequential CA aggregation (pH 12, 298 K) including a preliminary CMC at ca. 7 mM (no chiral selection), followed by a primary CMC at ca. 14 mM that allows chiral selection of binaphthyl enantiomers. In this work, DC is also shown to form stepwise preliminary and primary aggregates (ca. 3 mM DC and 9 mM DC, respectively, pH 12, 298 K) but the preliminary 3 mM DC aggregate is capable of chirally selective solubilization of the binaphthyl enantiomers. Higher-order, secondary bile aggregates of each of CA and DC show significantly degraded chiral selectivity. Diffusion NMR reveals that secondary micelles of CA exclude the BNDHP guests, while secondary micelles of DC accommodate guests, but with a loss of chiral selectivity. These data lead to the hypothesis that secondary aggregates of DC have an exposed binding site, possibly the 7α-edge of a bile dimeric unit, while secondary CA micelles do not present binding edges to the solution, potentially instead exposing the three alcohol groups on the hydrophilic α-face to the solution.

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Synthesis and Resolution of the Atropisomeric 1,1'-Bi-2-naphthol: An Experiment in Organic Synthesis and 2-D NMR Spectroscopy

Cited by 7 publications

References 8 publications

Proton NMR assignments for R,S‐1,1′‐binaphthol (BN) and R,S‐1,1′‐binaphthyl‐2,2′‐diyl hydrogen phosphate (BNDHP) interacting with bile salt micelles

Proton NMR assignments for R,S‐1,1′‐binaphthol (BN) and R,S‐1,1′‐binaphthyl‐2,2′‐diyl hydrogen phosphate (BNDHP) interacting with bile salt micelles

Hot-stage microscopy - Direct Analysis in Real-time mass spectrometry (HDM) as a novel tool for monitoring thermally-driven reactions on a small scale

Stepwise Aggregation of Cholate and Deoxycholate Dictates the Formation and Loss of Surface-Available Chirally Selective Binding Sites

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