2764-92-3Relevant academic research and scientific papers
Additions of benzylsulfonium ylides to aldehydes and ketones: Are they under kinetic or thermodynamic control?
Aggarwal, Varinder K.,Calamai, Simone,Ford, J. Gair
, p. 593 - 599 (2007/10/03)
The reaction of benzylsulfonium ylides with aromatic aldehydes gives predominantly trans epoxides whilst aliphatic aldehydes give mixtures of cis and trans epoxides. In order to probe the origin of the diastereoselectivity, single diastereoisomers of betaine intermediates were prepared by independent methods and subjected to ring closure and cross-over experiments. It was found that anti betaines derived from aliphatic and aromatic aldehydes gave exclusively trans epoxides. syn Betaines derived from aromatic aldehydes also gave exclusively trans epoxides whilst syn betaines derived from aliphatic aldehydes gave mixtures of cis and trans epoxides. From ring closure experiments in the presence of a more reactive aldehyde (cross-over experiments) it was found that anti betaines derived from aliphatic and aromatic aldehydes gave epoxides without incorporation of the more reactive aldehyde. In contrast, syn betaines derived from aromatic aldehydes gave exclusively epoxides derived from the more reactive aldehyde whilst syn betaines derived from aliphatic aldehydes gave mixtures of epoxides. These experiments indicated that the high trans selectivity observed in epoxidation with aromatic aldehydes is a result of irreversible formation of the anti betaine and reversible formation of the syn betaine. With aliphatic aldehydes the lower selectivity results from only partial reversibility in formation of the syn betaine.
STEREOCHEMISTRY OF ORGANIC SULPHUR COMPOUNDS. Part 13. CONFIGURATIONAL ASSIGNMENT OF DIASTEREOISOMERS OF 2-METHYLSULPHINYL-1,2-DIPHENYLETHANOL AND THEIR O-METHYL AND O-ACETYL DERIVATIVES
Brunet, E.,Ruano, J. L. Garcia,Martinez, M. C.,Rodrigez, J. H.,Alcudia, F.
, p. 2023 - 2034 (2007/10/02)
The synthesis, isolation and conformational analysis of the diastereomeric 2-methylsulphinyl-1,2-diphenylethanol and its O-methyl and O-acetyl derivatives are reported.Chemical correlations and the study of the influence of solvent polarity changes on the coupling constants have permitted the configurational assignment.Lanthanide shift reagents have been used also to this effect.The role of hydrogen bonding in the hydroxysulphoxides has been evaluated in diluted solutions by IR and NMR spectroscopy.A donor-acceptor interaction between oxygen and sulphur has been invoked to explain the differences in conformational behaviuor between epimeric sulphoxides at sulphur atom.
REACTION OF THIOLSULFINATES WITH TRIHALOACETIC ANHYDRIDES. II. ADDITION OF SULFENYL TRIHALOACETATES TO OLEFINS
Morishita, Tsuyoshi,Furukawa, Naomichi,Oae, Shigeru
, p. 2539 - 2546 (2007/10/02)
Treatment of thiolsulfinates with trifluoro- or trichloroacetic anhydride at -20 deg C in the presence of various olefins in carbon tetrachloride afforded the corresponding β-trifluoro- or trichloroacetoxy sulfides in good yields.The β-trihaloacetoxy sulfides are considered to be resulted by the electrophilic addition of the sulfenyl trihaloacetates, formed as transient intermediates, to olefins.The addition takes place stereospecifically in trans manner and the regioselectivity for the addition with unsymmetrical olefins obeyed the Markownikoff orientation rule, except 3,3-dimethyl-1-butene which gave initially the anti-Markownikoff product 3 due to the steric hindrance, however the adduct 3 is readily converted to the Markownikoff product 22 upon heating.Since the addition is highly regioselective and stereospecific, this is a very convenient procedure for the syntheses of β-trihaloacetoxy sulfides.
