Prevost, Michel; Dostie, Starr; Waltz, Marie-Eve; Guindon, Yvan published the artcile< Investigation of diastereoselective acyclic α-alkoxydithioacetal substitutions involving thiacarbenium intermediates>, Computed Properties of 617-55-0, the main research area is diastereoselective acyclic alkoxydithioacetal substitution thiacarbenium intermediate.
Reported herein is an exptl. and theor. study that elucidates why silylated nucleobase additions to acyclic α-alkoxythiacarbenium intermediates proceed with high 1,2-syn stereocontrol (anti-Felkin-Anh), which is opposite to what would be expected with corresponding activated aldehydes. The acyclic thioaminals formed undergo intramol. cyclizations to provide nucleoside analogs with anticancer and antiviral properties. The factors influencing the selectivity of the substitution reaction have been examined thoroughly. Halothioether species initially form, ionize in the presence (low dielec. media) or absence (higher dielec. media) of the nucleophile, and react through SN2-like transition structures (TS A and D), where the α-alkoxy group is gauche to the thioether moiety. An important, and perhaps counterintuitive, observation in this work was that calculations done in the gas phase or low dielec. media (toluene) are essential to locate the product- and rate-determining transition structures (C-N bond formation) that allow the most reasonable prediction of selectivity and isotope effects for more polar solvents (THF, MeCN). The ΔΔG (GTSA-TSD) obtained in silico are consistent with the preferential formation of 1,2-syn product and with the trends of stereocontrol displayed by 2,3-anti and 2,3-syn α,β-bis-alkoxydithioacetals.
Journal of Organic Chemistry published new progress about Chiral induction. 617-55-0 belongs to class esters-buliding-blocks, and the molecular formula is C6H10O5, Computed Properties of 617-55-0.
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