Chiral sulfur-reagents for the preparation of optically active epoxides

Pyridyl and Furyl Epoxides of More Than 99% Enantiomeric Purities: The Use of a Phosphazene Base

“…It is worth noting that only the trans-epoxide was formed, in agreement with previous results concerning diaromatic epoxides [6,11] obtained with NaH as base; only in the case of 2-pyridyl epoxide (1) was 12% of the cis-isomer obtained.…”

“…[6,9,11] It thus appeared that EtP2 leads to the same configuration as NaH and one can postulate that the model [9,12] shown in Figure 1 holds. Therefore the same structure was assigned to the (؉, EtOH)-isomers obtained for the new and unknown trans-epoxides 1,2,3 and 4: (1R,2R)-1, (1R,2R)-2, (1S,2R)-3 and (1R,2R)-4.…”

“…The sulfonium salt 7 was prepared following Vedej's method: [10] H NMR spectroscopy. [6,11] Table 3. Conditions and parameters for HPLC analyses of epoxides 1-4 on chiral columns (for analysis of epoxide 5 see ref.…”

Synthesis and reactions of benzotriazolyl epoxides

“…According to a study of the electronic structure of 1-vinyl-1H-benzotriazoles, 10 the energy of the MO of the C=C bond is higher than that of those localized on N-3. The order of these two MOs here is reversed compared to that of 1-allylbenzotriazole, which is oxidized to the 3-N-oxides.…”

Synthesis and Diels-Alder reactivity of sulfinyl homo- and heterodienes obtained via enantiopure sulfenic acids

“…2-Hydroxy-1-phenylethanethiol, 11f, and 2-hydroxy-2-phenylethanethiol, 11g, were exploited as chiral control elements since the chiral auxiliaries derived from these vicinal hydroxythiols may be removed by phenyloxiran formation. 9 Moreover, we decided to compare the behavior of the structural isomers 11f and 11g, in order to evaluate whether the position of the asymmetric carbon with respect to the sulfur atom could have any effect on the asymmetric induction during the thermolysis of sulfoxides 13 (Scheme 1). The commercially available [(1S)-endo]-(-)-borneol was easily transformed into the corresponding thiol 11e which represented a suitable precursor of sulfinyl-dienes 5-10e possessing the remarkable characteristics of the camphor skeleton but having no possibilities of intramolecular hydrogen bonding.…”