Moon HR, Siddiqui MA, Sun G, Filippov IV, Landsman NA, Lee YC, Adams KM, Barchi JJ, Deschamps JR, Nicklaus MC, Kelley JA, Marquez VE. Using conformationally locked nucleosides to calibrate the anomeric effect: Implications for glycosyl bond stability.
Tetrahedron 2010;
66:6707-6717. [PMID:
21052524 PMCID:
PMC2967253 DOI:
10.1016/j.tet.2010.06.044]
[Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Steric and electronic parameters such as the anomeric effect (AE) and gauche effect play significant roles in steering the North ⇆ South equilibrium of nucleosides in solution. Two isomeric oxa-bicyclo[3.1.0]hexane nucleosides that are conformationally locked in either the North or the South conformation of the pseudorotational cycle were designed to study the consequences of having the AE operational or not, independent of other parameters. The rigidity of the system allowed the orientation of the orbitals involved to be set in "fixed" relationships, either antiperiplanar where the AE is permanently "on", or gauche where the AE is impaired. The consequences of these two alternatives were subject to high-level calculations and measured experimentally by x-ray crystallography, hydrolytic stability of the glycosyl bond, and pKa values.
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