Thermal racemization of benzyl p-tolyl sulfoxide and thermal rearrangement of benzyl p-toluenesulfenate

Miller, Edward G.; Rayner, Dennis R.; Thomas, Harold T.; Mislow, Kurt

doi:10.1021/ja01020a020

Cited by 87 publications

(65 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…19 Allylic sulfoxides undergo thermal racemization by a cyclic rearrangement mechanism, with activation parameters DH { ¼ 23.1 kcal/mol and DS { ¼ À4.9 eu. 20 Quantum-mechanical calculations can determine mechanisms and energy barriers for chemical processes, including mechanisms of racemization.…”

Section: Introductionmentioning

confidence: 99%

Pyramidal inversion mechanism of simple chiral and achiral sulfoxides: A theoretical study

2007

View full text Add to dashboard Cite

The pyramidal inversion mechanism of simple sulfoxides was studied, employing ab initio and DFT methods. The convergence of the geometrical and energetic parameters of H2SO and DMSO with respect to the Hamiltonian and basis set was analyzed in order to determine a computational level suitable for methyl phenyl sulfoxide (3), methyl 4-cyanophenyl sulfoxide (4), diphenyl sulfoxide (5), 4,4'-dicyanodiphenyl sulfoxide (6), benzyl methyl sulfoxide (7) and benzyl phenyl sulfoxide (8). The DFT B3LYP/6-311G(d,p) level was chosen for further calculations of larger sulfoxides. The barriers DeltaE calculated for the pyramidal inversion mechanism of sulfoxides 3-8 are in the range of 38.7-47.1 kcal/mol. These values are in good agreement with the experimental barriers for racemization via the pyramidal inversion mechanism. A resonance effect of a phenyl ring selectively stabilizes the transition state conformations, decreasing the energy barrier for pyramidal inversion by about 3 kcal/mol, compared to a similar molecule without a phenyl substituent. Introducing electron withdrawing groups (cyano) at the para positions of the phenyl ring(s) causes a further decrease of the energy barrier.

show abstract

Section: Introductionmentioning

confidence: 99%

Pyramidal inversion mechanism of simple chiral and achiral sulfoxides: A theoretical study

2007

View full text Add to dashboard Cite

show abstract

“…[14][15][16][17] By contrast, it was proposed that the solution-phase thermal decomposition of benzyl p-toluenesulfenate mainly to the sulfoxide went by a concerted mechanism. 18 To the best of our knowledge, no gas-phase data regarding thermolysis of sulfenic esters exist. The experimental heat of formation is known for CH 3 SO • , 19 but not for any other sulfinyl radical.…”

Section: Introductionmentioning

confidence: 99%

“…Mislow and co-workers experimentally studied the isomerization of benzyl p-toluenesulfenate to benzyl p-tolyl sulfoxide in benzene. 18 They obtained ∆H q ) 30 kcal/ mol and ∆S q ) -2 eu. Isotopic labeling experiments indicated a partial retention of configuration at the benzyl carbon during the rearrangement.…”

mentioning

confidence: 97%

Thermochemistry of Sulfenic Esters (RSOR‘): Not Just Another Pretty Peroxide

Gregory

Jenks

1998

J. Org. Chem.

View full text Add to dashboard Cite

A computational study on the thermochemistry of several simple sulfenic acids (RSOH) and esters (RSOR′) is reported. The enthalpies of R-S, S-O, and O-R′ homolytic cleavage are calculated at the G2 level of theory and compared to related peroxides and disulfides. Less expensive B3LYP calculations were unsatisfactory. When R and R′ are both alkyl, the O-C bond is expected to be the weakest in the molecule; for CH 3 SOCH 3 , C-S, S-O, and O-C bond dissociation enthalpies of 67, 64, and 49 kcal/mol are predicted by G2. Compared to peroxides, sulfenic esters are predicted to have weaker O-C bonds and S-O bonds that are stronger than the analogous O-O bonds. The C-S bonds of sulfenic esters are predicted to be somewhat stronger than those of disulfides. A rationalization is given for the observation that radical stabilization is greater for RSO• than ROO• , RSS• , or ROS • .

show abstract

“…[7] These two diastereotopic protons are ascribed to the chirality at sulfoxide, which generally requires > 35 kcal mol À1 for racemization. [15] The ESI-MS spectra, which show the molecular ion of [MÀCl] + , also support the formation of imidazolium salts.…”

Section: Sulfoxide-functionalized Imidazolium Salts and Silver(i) Commentioning

confidence: 82%

Coordination Chemistry of Highly Hemilabile Bidentate Sulfoxide N‐Heterocyclic Carbenes with Palladium(II)

Yu¹,

Wang²,

Chang³

et al. 2014

Chemistry An Asian Journal

View full text Add to dashboard Cite

Imidazolium salts, [RS(O)-CH2 (C3 H3 N2 )Mes]Cl (R=Me (L1a), Ph (L1b)); Mes=mesityl), make convenient carbene precursors. Palladation of L1a affords the monodentate dinuclear complex, [(PdCl2 {MeS(O)CH2 (C3 H2 N2 )Mes})2 ] (2a), which is converted into trans-[PdCl2 (NHC)2] (trans-4a; N-heterocyclic carbene) with two rotamers in anti and syn configurations. Complex trans-4a can isomerize into cis-4a(anti) at reflux in acetonitrile. Abstraction of chlorides from 4a or 4b leads to the formation of a new dication: trans-[Pd{RS(O)CH2(C3H2N2)Mes}2](PF6)2 (R=Me (5a), Ph (5b)). The X-ray structure of 5a provides evidence that the two bidentate SO-NHC ligands at palladium(II) are in square-planar geometry. Two sulfoxides are sulfur- and oxygen-bound, and constitute five- and six-membered chelate rings with the metal center, respectively. In acetonitrile, complexes 5a or 5b spontaneously transform into cis-[Pd(NHC)2(NCMe)2](PF6)2. Similar studies of thioether-NHCs have also been examined for comparison. The results indicate that sulfoxides are more labile than thioethers.

show abstract

Thermal racemization of benzyl p-tolyl sulfoxide and thermal rearrangement of benzyl p-toluenesulfenate

Cited by 87 publications

References 1 publication

Pyramidal inversion mechanism of simple chiral and achiral sulfoxides: A theoretical study

Pyramidal inversion mechanism of simple chiral and achiral sulfoxides: A theoretical study

Thermochemistry of Sulfenic Esters (RSOR‘): Not Just Another Pretty Peroxide

Coordination Chemistry of Highly Hemilabile Bidentate Sulfoxide N‐Heterocyclic Carbenes with Palladium(II)

Contact Info

Product

Resources

About