Induction of a Preferred Twist in a Biphenyl Core by Stereogenic Centers: A Novel Approach to the Absolute Configuration of 1,2- and 1,3-Diols

Superchi, Stefano; Casarini, Daniele; Laurita, Alessandro; Bavoso, Alfonso; Rosini, Carlo

doi:10.1002/1521-3773(20010119)40:2<451::aid-anie451>3.0.co;2-2

Cited by 102 publications

(68 citation statements)

References 61 publications

(2 reference statements)

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“…The consistently positive Cotton effects at longer wavelengths and negative Cotton effect at shorter wavelengths are typical of the (S) compound, whereas an opposite CD pattern is exhibited by the (R) compound. [56] Therefore, as in the related Bin derivatives and peptides, [27] the CD spectrum reflects the configurational properties of the [20-C-6]-Bip residue, but does not provide any conformational information. …”

Section: Conformational Characterization Of Boc-[20-c-6]-bip-(aib) 6 supporting

confidence: 54%

Synthesis of the First Axially Dissymmetric,Cα,α-Disubstituted Glycine Containing a Crown Ether Receptor, and the Conformational Preferences of a Model Peptide

et al. 2002

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Keywords: Atropoisomeric amino acids / Axial chirality / C α,α -disubstituted glycine / Crown compounds / Side-chain modified amino acids Racemic and enantiomerically enriched N α -protected methyl 6-amino-1,11-(20-crown-6)-6,7-dihydro-5H-dibenzo[a,c]-cycloheptene-6-carboxylates (Boc-[20-C-6]-Bip-OMe) (RS)-Ia, (R)-Ia and (S)-Ia have been synthesized by phase-transfer dialkylation of the 4-chlorobenzylidene derivative of glycine tert-butyl ester, with both racemic and resolved (both enantiomers) 2,2Ј-bis(bromomethyl)-6,6Ј-dimethoxy-1,1Ј-biphenyl being used as alkylating agents. Demethylation of the resulting (RS)-, (R)-and (S)-H-[MeO] 2 -Bip-OtBu, followed by esterification and N α -Boc protection, gave (RS)-, (R)-and (S)-Boc-[HO] 2 -Bip-OMe. Cyclization with Cs 2 CO 3 /DMF and pentaethylene glycol ditosylate afforded the crown-carrier C α,α -disubstituted glycines (RS)-Ia, (R)-Ia and (S)-Ia, possessing only axial dissymmetry. Although (R)-Ia and (S)-Ia are enantiomerically stable in solution at 110°C, they were

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Section: Conformational Characterization Of Boc-[20-c-6]-bip-(aib) 6 supporting

confidence: 54%

Synthesis of the First Axially Dissymmetric,Cα,α-Disubstituted Glycine Containing a Crown Ether Receptor, and the Conformational Preferences of a Model Peptide

et al. 2002

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“…Moreover, we have recently demonstrated that the NMR-based Mosher approach is sometimes not reliable in the AC assignment to chiral diols, 30 whereas chiroptical methods, that is, ECD, vibrational circular dichroism (VCD), and optical rotatory dispersion (ORD), can provide more general and reliable tools for this task. 31 At first, we attempted to apply for AC assignment to 1 and 2 the use of biphenyl chiroptical probes, 32,33 that we recently demonstrated to be particularly straightforward for naturally occurring diols. 30 However, compounds 1 and 2 did not allow biphenyl derivatization, as a consequence of their low solubility in the required aprotic solvents.…”

Section: Resultsmentioning

confidence: 99%

Further secondary metabolites produced by the fungus Pyricularia grisea isolated from buffelgrass (Cenchrus ciliaris)

et al. 2020

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The fungal pathogen Pyricularia grisea has been studied to evaluate its production of phytotoxins for the biocontrol of the buffelgrass (Cenchrus ciliaris L.) weed. A first investigation allowed to isolate several new and known phytotoxic metabolites. However, the further investigation on the organic extract obtained from the fungus liquid culture showed the presence of other metabolites possibly contributing to its phytotoxicity. Thus, four known metabolites were isolated and identified by spectroscopic (nuclear magnetic resonance [NMR] and high‐resolution electrospray ionization mass spectrometry [HRESIMS]) methods as dihydropyriculol (1), epi‐dihydropyriculol (2), 3‐methoxy‐6,8‐dihydroxy‐3‐methyl‐3,4‐dihydroisocoumarin (3), and (R)‐mevalonolactone (4). The absolute configuration of 1–3 was determined for the first time by a computational analysis of their electronic circular dichroism (ECD) spectra. When the isolated compounds were bioassayed at a concentration of 5 × 10–3 M in a buffelgrass coleoptile and radicle elongation test no toxicity was detected. On the contrary, compounds 1 and 3 showed a significant stimulating effect of radical elongation. Furthermore, the difference in growth stimulation between 1 and its epimer 2 highlights the tight relationship between absolute configuration and biological activity of these fungal metabolites.

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“…However, a significant limitation of this approach can occur in systems undergoing conformational changes and in applications to acyclic compounds. The flexibility of such systems may cause difficulties in the correct stereochemical assignment [21][22][23].…”

Section: Introductionmentioning

confidence: 91%

Complementarity of electronic and vibrational circular dichroism based on stereochemical studies of vic-diols

Jawiczuk

Górecki

Masnyk

et al. 2015

TrAC Trends in Analytical Chemistry

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Induction of a Preferred Twist in a Biphenyl Core by Stereogenic Centers: A Novel Approach to the Absolute Configuration of 1,2- and 1,3-Diols

Cited by 102 publications

References 61 publications

Synthesis of the First Axially Dissymmetric,Cα,α-Disubstituted Glycine Containing a Crown Ether Receptor, and the Conformational Preferences of a Model Peptide

Synthesis of the First Axially Dissymmetric,Cα,α-Disubstituted Glycine Containing a Crown Ether Receptor, and the Conformational Preferences of a Model Peptide

Further secondary metabolites produced by the fungus Pyricularia grisea isolated from buffelgrass (Cenchrus ciliaris)

Complementarity of electronic and vibrational circular dichroism based on stereochemical studies of vic-diols

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