The crystal structure and absolute configuration of (+)-methyl-p-tolyl sulfoxide

Camp, U. de la; Hope, H.

doi:10.1107/s0567740870003217

Cited by 47 publications

(15 citation statements)

References 6 publications

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“…It is another example of a simply conjugated system, and a crystal structure is known for the closely related p-tolyl methyl sulfoxide. 29 Diphenyl sulfoxide is the archetypal diaryl sulfoxide and also serves as a control for measuring effects on 3. In addition, it is another compound whose SO bond energy is known.…”

Section: Resultsmentioning

confidence: 99%

Effects of Conjugation and Aromaticity on the Sulfoxide Bond¹

1996

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An ab initio computational study on a series of sulfoxides is reported. The SO bond dissociation energy (BDE) of sulfoxides in which the sulfur atom is included in a formally aromatic ring (e.g., thiophene sulfoxide) is found to be decreased by as much as 25 kcal/mol, compared to DMSO. A complementary effect is observed for sulfoxides in which the sulfur is included in a formally antiaromatic ring (e.g., thiirene sulfoxide), in which SO BDEs are increased by as much as 15 kcal/mol. Both effects are attenuated by benzannulation. Examination of calculated geometries and isodesmic reactions with pure hydrocarbons leads to the conclusion that the observed effects are due to a severe disruption of the (anti) aromaticity of the sulfurcontaining ring on oxidation. The cyclic sulfoxides appear to be neither significantly aromatic nor antiaromatic by energetic considerations. No significant SO bond strength effect is observed for simple conjugation. Inversion barriers for several sulfoxides are also calculated. Disciplines Chemistry CommentsReprinted (adapted) An ab initio computational study on a series of sulfoxides is reported. The SO bond dissociation energy (BDE) of sulfoxides in which the sulfur atom is included in a formally aromatic ring (e.g., thiophene sulfoxide) is found to be decreased by as much as 25 kcal/mol, compared to DMSO. A complementary effect is observed for sulfoxides in which the sulfur is included in a formally antiaromatic ring (e.g., thiirene sulfoxide), in which SO BDEs are increased by as much as 15 kcal/mol. Both effects are attenuated by benzannulation. Examination of calculated geometries and isodesmic reactions with pure hydrocarbons leads to the conclusion that the observed effects are due to a severe disruption of the (anti) aromaticity of the sulfur-containing ring on oxidation. The cyclic sulfoxides appear to be neither significantly aromatic nor antiaromatic by energetic considerations. No significant SO bond strength effect is observed for simple conjugation. Inversion barriers for several sulfoxides are also calculated.

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Section: Resultsmentioning

confidence: 99%

Effects of Conjugation and Aromaticity on the Sulfoxide Bond¹

1996

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“…It therefore seems likely that, in the case of sulphone formation from 2g and 2j, both oxidations occur without the substrate leaving the enzyme's active site; it may therefore not be possible to directly determine the stereoselectivity of the second oxidation. The assignment of absolute.stereochemistry to the predominant sulphoxide enantiomers in Table 1 follows from the results reported for the absolute stereochemistry of alkyl aryl sulphoxides of known optical rotation (14,15,19,20).…”

Section: *Accompanied By Sulphone (5%)mentioning

confidence: 94%

The oxidation of organic sulphides by Mortierellaisabellina. 2. Effects of substituents on the stereochemistry of sulphoxide formation

Holland¹,

Pöpperl²,

Ninniss³

et al. 1985

Can. J. Chem.

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A series of para-substituted alkyl aryl sulphides has been transformed stereoselectively to the sulphoxide by incubation with the fungus Mortierella isabellina. The enantiorneric purity of the products was dependent on the nature of substitution in the aromatic ring and at sulphur. Comparisons of the enantiomeric purities obtained from sulphides with para substituents of the same steric size but different electronic properties indicate that the stereoselectivity of S oxidation is susceptible to electron withdrawing or donating factors. This conclusion lends credence to a stepwise oxidation mechanism involving an electron deficient sulphur intermediate. 18 (1985).Par incubation avec des champignons Mortierella isabellina, on a transform6 stCrCosClectivement en sulfoxydes une sCrie de sulfures d'alkyles et d'aryles substituCs en para. La puretC CnantiomCrique des produits dCpend de la nature des substituants sur le noyau aromatique et au niveau du soufre. En se basant sur une comparaison des puretCs CnantiomCriques obtenues avec des sulfures portant des substituants en para qui ont des encombrernents stCriques sernblables rnais des propriCtCs Clectroniques differentes, on peut dCduire que la stCrCosClectivitC de l'oxydation du soufre est susceptible aux factuers Clectro-affinitaires ou Clectro-donneurs des substituants. Cette conclusion supporte le concept d'un mCcanisme par Ctape irnpliquant un intermediaire sulfur6 dkficient en Clectrons.[Traduit par le journal]In spite of the continued interest in chiral sulphoxides, both in the study of sulphur stereochemistry (1) and as intermediates in asymmetric synthesis (2), the best direct chemical methods for their generation from sulphides (3) have not yet achieved the high degree of enantiomeric purity desirable in modem asymmetric synthesis. High enantiomeric excesses (>35%) are routinely available for p-tolyl alkyl sulphoxides (only) by a modification (4) of the Anderson synthesis (5) using sulfinate esters, or by the use of biological oxidizing agents employing sulphides as substrates.In the latter area, the use of actively growing or resting cultures of fungi has been the most widely used technique for the production of sulphoxides of good optical purity (6-8).Other methods of biotransformation, using enzymes of mammalian origin (9,lO) or peroxide oxidation in the presence of enzyme templates (1 l), are not generally applicable to preparative scale work.In an extension of our earlier work on the mechanism of alkyl aryl sulphide oxidation by the fungus Mortierella isabellina (12), in which we proposed that cytochrome P-450 dependent mono-oxygenase enzymes of the fungus were responsible for oxidation at sulphur, we have now studied the effects of substitution at the para position of the aromatic ring, and at sulphur, on the degree of enantiomeric enrichment of the resultant sulphoxide. The sulphides used in this study, 1 and 4, gave the corresponding sulphoxides, 2 and 5, respectively, as major products on incubation with M. isabellina; this is summarized in Table ...

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“…The conformation around the central S(1)-X(3) bond is transoid, the torsional angle C(2)-C(3)-S(1)-C(30), defining the orientation of the phenyl ring and the fluoromethyl moiety, being 164.5(2)". The molecular geometry at S(l) conforms to that found for relatedp-tolylsulfinyl derivatives (17)(18)(19)(20)(21).…”

Section: Structural Assignmerltsmentioning

confidence: 79%

Stereoselective oxirane formation by reaction of diazomethane on 1-fluoro-3-[(4-methylphenyl)sulfinyl]-3-phenylpropan-2-one

Bravo¹,

Frigerio²,

Fronza³

et al. 1994

Can. J. Chem.

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F'IERFRANCESCO BRAVO, MASSIMO FRIGERIO, GIOVANNI FRONZA, VADIM SOLOSHONOK, FIORENZA VIANI, GIANCARLO CAVICCHIO, GIANCARLO FABRIZI, and DORIANO LAMBA. Can. J. Chem. 72, 1769Chem. 72, (1994. (2S,2'R,Rs)-2-(Fluoromethyl)-2-{[(4-methylphenyl)sulfinyl][phenyl]methyl)oxirane (4) was obtained in high chemical yield and with high diastereoselectivity by reacting diazomethane with pure (3R,Rs)-1-fluoro-3-[(4-methylphenyl)sulfinyl]-3-pheny1-propan-2-one (3), but also with its (3S,Rs)-3-diastereoisomer, in the latter case through inversion of the configuration at carbon 3. The corresponding methyl en01 ethers 6 were isolated as by-products. NMR experiments and molecular modelling calculations were performed in order to clarify the equilibria in solution and the preferred conformations of both ketones 3. Several variously substituted, sulfur-free tertiary a-(fluoromethy1)carbinols were obtained from the main reaction product (2S,2'R,Rs)-4 through appropriate elaborations of the sulfinyl group and of the oxirane ring. The structure of (2S,2'R,Rs) Le (2S,2'R,Rs)-2-(fluoromCthyl)-2-{[(4-mCthylphCnyl)sulfinyl][phCnyl]mCthyl)oxirane (4) fut obtenu avec d'excellents rendements chimiques et avec une diastCrCosClectivit6ClevCe en faisant rCagir du diazomkthane avec de la (3R,Rs)-1-fluoro-3-[(4-mCthylphCnyl)sulfinyl]-3-phCnylpropan-2-(3) pure ou sous la forme de mClange avec le diastCrCoisomkre (3S,Rs)-(3); dans ce dernier cas, la rCaction se fait par le biais d'une inversion de configuration au niveau du carbone 3. Les Cthers Cnoliques mCthyles correspondants (6) sont isolCs comme sous-produits. Des experiences de RMN et des calculs de modelage molCculaire ont Ct C exCcutCs pour clarifier les Cquilibres en solution et les conformations privilCgiCes des deux cCtones 3. On a prepare de nombreux a-(fluoromCthy1)carbinols tertiaires sans soufre et portant divers groupes fonctionnels par Claborations appropriCes du groupe fonctionnel sulfinyle et de l'anneau oxirane i partir du produit principal de la rCaction le (2S,2'R,Rs)-4. La structure du (2S,2'R,Rs)-4 a Ct C determinee par diffraction des rayons X du dCrivC aliphatique (2S,2'R,Rs)-l-bromo-3-fluoro-2'-{[(4-mCthylphCny1)sulfinyl I[phCnyl]mCthyl)propan-2-01 (7).[Traduit par la redaction]

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The crystal structure and absolute configuration of (+)-methyl-p-tolyl sulfoxide

Cited by 47 publications

References 6 publications

Effects of Conjugation and Aromaticity on the Sulfoxide Bond¹

Effects of Conjugation and Aromaticity on the Sulfoxide Bond¹

The oxidation of organic sulphides by Mortierellaisabellina. 2. Effects of substituents on the stereochemistry of sulphoxide formation

Stereoselective oxirane formation by reaction of diazomethane on 1-fluoro-3-[(4-methylphenyl)sulfinyl]-3-phenylpropan-2-one

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The crystal structure and absolute configuration of (+)-methyl-p-tolyl sulfoxide

Cited by 47 publications

References 6 publications

Effects of Conjugation and Aromaticity on the Sulfoxide Bond1

Effects of Conjugation and Aromaticity on the Sulfoxide Bond1

The oxidation of organic sulphides by Mortierellaisabellina. 2. Effects of substituents on the stereochemistry of sulphoxide formation

Stereoselective oxirane formation by reaction of diazomethane on 1-fluoro-3-[(4-methylphenyl)sulfinyl]-3-phenylpropan-2-one

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Effects of Conjugation and Aromaticity on the Sulfoxide Bond¹

Effects of Conjugation and Aromaticity on the Sulfoxide Bond¹