Conformational analysis. 32. Conformational energies of methyl sulfide, methyl sulfoxide, and methyl sulfone groups

Eliel, Ernest L.; Kandasamy, Duraisamy

doi:10.1021/jo00886a026

Cited by 50 publications

(29 citation statements)

References 3 publications

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“…The equatorial conformation was found to be more stable by 2.3 kcal·mol Ϫ1 . The good agreement with the A value given for a cyclohexyl methyl sulfone (2.5 kcal·mol Ϫ1 ) [17] shows the reliability of the AM1 calculations.…”

Section: Confirmation Of the Stereochemistrysupporting

confidence: 74%

Synthesis and Stereochemical Assignments ofcis- andtrans-1-Amino- 4-ethylcyclohexa-2,5-diene as Models for Amiclenomycin

et al. 2002

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As an approach to the synthesis of amiclenomycin (1), we describe here the synthesis of a 1-aminocyclohexa-2,5-diene moiety. The cis isomer 2 was obtained by means of a Diels− Alder reaction between trans-1,2-bis(phenylsulfonyl)ethylene and N-(allyloxycarbonyl)hexa-1,3-diene (13), followed by reductive elimination of the phenylsulfinyl groups. To obtain the trans isomer 3, O-(trimethylsilyl)hexa-1,3-diene (16) was used. This afforded the cis-hydroxylated Diels−Alder adducts 18, which were transformed into the corresponding

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Section: Confirmation Of the Stereochemistrysupporting

confidence: 74%

Synthesis and Stereochemical Assignments ofcis- andtrans-1-Amino- 4-ethylcyclohexa-2,5-diene as Models for Amiclenomycin

et al. 2002

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“…(a) Inversion of the cyclohexane ring is possible only for 1, because the tert-butyl group in 2 and 3 retains the equatorial position; its conformational energy ( A value) is much larger16 than that of any of the sulphur functions. [17][18][19] Even the smallest of these (SC6H5: 0.7-1.24 kcal rno1-I 17,19), however, shifts the conformational equilibrium of l a clearly to the equatorial side, so that its 'H and 13C NMR data (Table 1) are dominated by this rotamer. This is confirmed by a comparison of its 'H and 13C chemical shifts with those of 2a and 3a, although the signals which are most sensitive to the stereochemical position of the SC6H5 group (H-1 and C-3,s) seem to indicate the presence of a small proportion of the axial cyclohexyl phenyl sulphide.…”

Section: 'H and 13c Nmr And Stereochemical Considerationsmentioning

confidence: 99%

¹H, ¹³C, ¹⁷O and ³³S NMR investigation of some cyclohexyl phenyl sulphides, sulphoxides and sulphones

Duddeck

Korek

Rosenbaum

et al. 1986

Magnetic Reson in Chemistry

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The '€I and -C NMR signals of cyclohexyl phenyl sulphides, sulphoxides and sulphones were almost completely assigned, and the effects of diastereotopism in cis-4-tert-butylcyclohexyl phenyl sulphoxide were rationalized. Substituent effects on the "0 chemical sbift of numerous sulphoxides and sulphones are discussed. An unusual paramagnetic y gauche effect on the "S nucleus was detected in cis-4-tert-butylcyclohexyl phenyl sulphone.

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“…As an initial test, 4 was incorporated within a model peptide (Ac‐GPP X PPGY‐NH 2 ) that has been previously employed to quantify the polyproline II helix propensities of both canonical and unnatural amino acids . Using standard amide coupling conditions with HBTU as a coupling reagent, poor incorporation of 4 was observed, potentially due to the steric bulk resulting from β‐substitution with the sulfone . However, amide coupling proceeded effectively using COMU as a coupling reagent in the presence of catalytic DMAP (Scheme ).…”

Section: Resultsmentioning

confidence: 99%

“…[43][44][45][46][47][48] Using bulk resulting from β-substitution with the sulfone. [49,50] However, amide coupling proceeded effectively using COMU as a coupling reagent [51] in the presence of catalytic DMAP (Scheme 4). Alternatively, amide coupling was also accomplished using COMU and mild heating (40 C, 2 hours).…”

Section: Resultsmentioning

confidence: 99%

Synthesis of peptides with cysteine sulfinic acid via the cysteine methoxybenzyl sulfone

Urmey

Zondlo

2019

Peptide Science

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Cysteine sulfinic acid is a protein posttranslational modification that is formed under oxidative conditions and is regulated both enzymatically and nonenzymatically. Cysteine oxidation to the sulfinic acid has been observed broadly throughout the proteome and can induce activation or inhibition of function in proteins. Recently, wide‐scale, reversible regulation of the sulfinic acid state of cysteine within proteins was identified, posing new questions in cysteine sulfinic acid biology. Existing methods to synthesize peptides with cysteine sulfinic acid can suffer from low yield, due to the formation of side products in the disulfide, sulfenic acid, and/or sulfonic acid oxidation states. Herein, a method for the synthesis of peptides with cysteine sulfinic acids was developed, via protection of cysteine sulfinic acid as the methoxybenzyl (Mob) sulfone. Cysteine Mob sulfone was synthesized as an Fmoc amino acid in one step from the commercially available Mob‐protected Fmoc‐cysteine (Fmoc‐Cys(Mob)‐OH). This amino acid was directly incorporated into peptides via solid‐phase peptide synthesis. Alternatively, peptides were synthesized using Fmoc‐Cys(Mob)‐OH, followed by subsequent oxidation within peptides of the thioether to the Mob sulfone via H2O2 and catalytic niobium carbide. Deprotection of peptides under strongly acidic conditions (50% triflic acid, 45% trifluoroacetic acid, 5% water) generated peptides with cysteine sulfinic acid. This approach was applied to the synthesis of peptides containing cysteine sulfinic acid within diverse peptide sequence contexts.

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Conformational analysis. 32. Conformational energies of methyl sulfide, methyl sulfoxide, and methyl sulfone groups

Cited by 50 publications

References 3 publications

Synthesis and Stereochemical Assignments ofcis- andtrans-1-Amino- 4-ethylcyclohexa-2,5-diene as Models for Amiclenomycin

Synthesis and Stereochemical Assignments ofcis- andtrans-1-Amino- 4-ethylcyclohexa-2,5-diene as Models for Amiclenomycin

¹H, ¹³C, ¹⁷O and ³³S NMR investigation of some cyclohexyl phenyl sulphides, sulphoxides and sulphones

Synthesis of peptides with cysteine sulfinic acid via the cysteine methoxybenzyl sulfone

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Conformational analysis. 32. Conformational energies of methyl sulfide, methyl sulfoxide, and methyl sulfone groups

Cited by 50 publications

References 3 publications

Synthesis and Stereochemical Assignments ofcis- andtrans-1-Amino- 4-ethylcyclohexa-2,5-diene as Models for Amiclenomycin

Synthesis and Stereochemical Assignments ofcis- andtrans-1-Amino- 4-ethylcyclohexa-2,5-diene as Models for Amiclenomycin

1H, 13C, 17O and 33S NMR investigation of some cyclohexyl phenyl sulphides, sulphoxides and sulphones

Synthesis of peptides with cysteine sulfinic acid via the cysteine methoxybenzyl sulfone

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¹H, ¹³C, ¹⁷O and ³³S NMR investigation of some cyclohexyl phenyl sulphides, sulphoxides and sulphones