Conformational Studies of Methyl 3-O-Methyl--D-arabinofuranoside: An Approach for Studying the Conform

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• 作者：Justin B. Houseknecht ; Patrick R. McCarren ; Todd L. Lowary ; and Christopher M. Hadad
• 刊名：Journal of the American Chemical Society
• 出版年：2001
• 出版时间：September 12, 2001
• 年：2001
• 卷：123
• 期：36
• 页码：8811 - 8824
• 全文大小：301K
• 年卷期：v.123,no.36(September 12, 2001)
• ISSN：1520-5126

文摘

A computational method for probing furanose conformation has been developed using a methylatedmonosaccharide derivative 1. First, a large library of conformers was generated by a systematic pseudo MonteCarlo search followed by optimization with the AMBER molecular mechanics force field. A subset of theseconformers was then subjected to ab initio and density functional theory calculations in both the gas andaqueous phases. These calculations indicate that entropic contributions to the Gibbs free energy are importantdeterminants of the Boltzmann distribution for the conformational preferences of 1 in the gas phase. Theresults obtained at each level of theory are discussed and compared with the experimentally determined conformerdistribution from NMR studies in aqueous solution. In addition, the ability of each level of theory to reproducethe experimentally measured ¹H-¹H coupling constants in 1 is discussed. Empirical Karplus equations anddensity functional theory methods were used to determine average ³J_H1,H2, ³J_H2,H3, and ³J_H3,H4 for each levelof theory. On the basis of this comparison, consideration of solvation with the MN-GSM model providedgood agreement with the experimental data.