Oxides of 1,3-dithiane and 1,3,5-trithiane. Diamagnetic anisotropy of carbon-sulfur bonds

Khan, Shakil Ahmed; Lambert, Joseph B.; Hernández, Oscar; Carey, Francis A.

doi:10.1021/ja00839a032

Cited by 53 publications

(22 citation statements)

References 7 publications

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“…In the 1 H NMR spectrum of IVa, the parameters of both AB quartets (δ 3.00, 3.59 and 3.22, 3.56 pm) are very similar. An analogous weak stereochemical dependence of the chemical shifts of the methylene protons in the SCH 2 SO fragment was observed previously for the chair-like conformers of 1,3-dithiane 1-oxide with axial and equatorial orientation of the sulfoxide group [8][9][10][11]. Thus we can conclude that the minor conformer of IVa has a boat structure with axial orientation of the sulfoxide oxygen atom.…”

Section: Chair Boatsupporting

confidence: 84%

Synthesis and Stereochemistry of 1H,5H-Naphtho[1,8-ef][1,3]dithiocine 2-Oxides

et al. 2005

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3-Substituted 1H,5H-naphtho [1,8-ef][1,3]dithiocines (R = H, Me, Ph, t-Bu) were oxidized with m-chloroperoxybenzoic acid to the corresponding 2-oxides having trans configuration (R ≠ H). According to the 1 H and 13 C NMR data (including NOESY experiments), the disubstituted compounds at room temperature exist in a boat conformation with equatorial orientation of the substituent on C 3 and oxygen atom on S 2 . The compound with no substituent on C 3 gives rise to a mixture of boat conformers with axial and equatorial sulfoxide oxygen atoms at a ratio of 83 : 17.

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Section: Chair Boatsupporting

confidence: 84%

Synthesis and Stereochemistry of 1H,5H-Naphtho[1,8-ef][1,3]dithiocine 2-Oxides

et al. 2005

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“…As estimated by NMR, the ratio of the 3.74, 3.82, and 3.92 diastereomers was 44:37:19. The 3.82 diastereomer 3 is the least soluble of these and was obtained in pure form, mp 216-217.5 °C and [«]24d +25°( c 1.3, chloroform), after recrystallization. Base-catalyzed cleavage of 3 gave (+)-l, [ ]20 +230°(c 1.0, ethanol), in 94% yield.…”

Section: Resultsmentioning

confidence: 99%

“…Recrystallization of the crude mixture of 2, 3, and 5 leads to the isolation of 3 The procedure in Scheme II is not as efficient as either of the modifications of Scheme I. Condensation of 2-lithio-1,3-dithiane with (+)-camphor proceeds in only 49% yield to 4. The corresponding reaction of 2-lithio-l,3-dithiane 1-oxide with (+)-camphor gives yields of 56-83%, depending on the conditions used, along with recovered (and optically active)…”

Section: Resultsmentioning

confidence: 99%

Optically active 1,3-dithiane 1-oxide: optical resolution and absolute configuration

Bryan¹,

Carey²,

Dailey³

et al. 1978

J. Org. Chem.

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“…Analysis of these spectra is not straightforward because both the syn and anti isomers of 5-de exist as a mixture of two equally populated conformations (6)(7)(8)(9) differing only by the location of the deuterium atoms. If both sides of the molecules of 5-de were independent of each other, the time-averaged spectrum observed at 25 °C should consist of only four lines resulting from the superposition of AX patterns.…”

Section: Resultsmentioning

confidence: 99%

The stereodependent effect of oxygen on the chemical shifts and vicinal coupling constants of tetrahydropyran

Canuel¹,

Jacques²

1976

J. Org. Chem.

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The analysis of the ' H NMR spectra of two selectively deuterated derivatives of tetrahydropyran at -115 O C has provided accurate values for proton chemical shifts and vicinal coupling constants about the C(2)-C(3) bond. A comparison with the corresponding parameters of cyclohexane allows a precise definition of the stereodependent effect of oxygen (3J2a3a, 3J2e3e, 3J2a3e are reduced while 3J2e3a is increased) in this fundamental molecule. An explanation of the trends observed is given and the conformational and stereochemical implications of the results 'are discussed.The field of conformational and stereochemical analysis of basic six-membered ring systems is often considered fundamental in organic chemistry. NMR spectroscopy ranks among the most useful tools of experimental investigation in this domain and, when appropriate reference parameters are available, its application to molecules with readily analyzable spectra has become rather straightforward.l Vicinal coupling constants recently published2 for cyclohexane-d8 have provided the reference basis for many applications through an empirically determined dependence on dihedral angles.It is well known that heteroatoms affect the values of vicinal couplings according to their electronegativity, and many efforts have been aimed at providing information on the magnitude of this effect. In particular, approximate coupling values have been proposed for pyranoid derivatives from studies on carbohydrate derivative^,^ but there is a t present no knowledge of the quantitative effect of oxygen in -CH2CH20-fragments from cyclic systems and more specifically from the parent compound, tetrahydrofuran.Because of the fundamental nature of tetrahydropyran both for theoretical reasons and for practical conformational and stereochemical applications to many classes of heterocyclic organic compounds, it appeared to us that accurate chemical shift and coupling information for this basic compound should be a necessary prerequisite to quantitative deductions which go beyond merely drawing parallels between carbocyclic and heterocyclic rings.Because of the complexity of the l H NMR spectrum of tetrahydropyran and the need to obtain very accurate coupling constants we have prepared stereospecifically deuterated derivatives with simpler spectra and because ring inversion is rapid a t normal room temperature4 we have analyzed the spectra at low temperatures in order to obtain parameters characteristic of the noninverting chair conformation of this molecule. ResultsAs illustrated in Scheme I, y-pyranone (2) obtained from chelidonic acid (1)5 was deuterated with deuterium gas in the presence of palladium on carbon to give a mixture of syn and anti isomers6 of tetrahydropyranone-cis-2,3,cis-5,644 ( 3 4 ) which were reduced with lithium aluminum deuteride to give the alcohols 4-d5 which were converted to tetrahydropyran-4,4,cis-2,3,cis-5,6-d6 (5-dG). Protonic exchange of the 01 deuterium in 3-d4 gave a mixture of syn and anti isomers tetrahydropyranone-2,6-d2 (3-dz) which were reduced t...

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Oxides of 1,3-dithiane and 1,3,5-trithiane. Diamagnetic anisotropy of carbon-sulfur bonds

Cited by 53 publications

References 7 publications

Synthesis and Stereochemistry of 1H,5H-Naphtho[1,8-ef][1,3]dithiocine 2-Oxides

Synthesis and Stereochemistry of 1H,5H-Naphtho[1,8-ef][1,3]dithiocine 2-Oxides

Optically active 1,3-dithiane 1-oxide: optical resolution and absolute configuration

The stereodependent effect of oxygen on the chemical shifts and vicinal coupling constants of tetrahydropyran

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