Conformational Domino Effect in Saccharides. 2. Anomeric Configuration Control

• Published in: Journal of organic chemistry Vol. 73; no. 18; pp. 7266 - 7279
• Main Authors: Roën, Alfredo, Mayato, Carlos, Padrón, Juan I, Vázquez, Jesús T
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 19.09.2008; Amer Chemical Soc
• Subjects: Carbohydrate Conformation; Carbohydrates with 4, 5, 6, ... C atoms, dissacharides and oligosaccharides; Carbohydrates. Nucleosides and nucleotides; Chemistry; Chemistry, Organic; Circular Dichroism; Disaccharides - chemical synthesis; Disaccharides - chemistry; Exact sciences and technology; Magnetic Resonance Spectroscopy - methods; Magnetic Resonance Spectroscopy - standards; Organic chemistry; Physical Sciences; Preparations and properties; Reference Standards; Rotation; Science & Technology; Stereoisomerism; ALKYL GLUCOPYRANOSIDES; METHOXYMETHYL GROUPS; C5-C6 BOND; ABSOLUTE-CONFIGURATION; D-MANNOSE DERIVATIVES; ROTAMER POPULATIONS; AB-INITIO; HYDROXYMETHYL GROUP CONFORMATION; ROTATIONAL POPULATION DEPENDENCE; COUPLING-CONSTANTS; Correlation; Configuration; Molecular structure; Twist angle; Aglycone; Bond angle; Prediction; Refractivity; Coupling constant; Oside; NMR spectrometry; Steric effect; Circular dichroism spectrometry; Glycoside; Beta anomer; Alpha anomer; Chemical synthesis; Solvent; Conformation
• ISSN: 0022-3263; 1520-6904
• DOI: 10.1021/jo801184q

A series of alkyl β-d-glucopyranosyl-(1→6)-α-d-glucopyranosides were synthesized and analyzed by NMR and CD techniques. As in their β-anomer series, the rotational populations of the hydroxymethyl group involved in the interglycosidic linkage (torsion angle ω) are shown to depend on the aglycon and the solvent. However, for this α-anomer series the rotational dependence arises directly from steric effects. Correlations between rotational populations and molar refractivity (MR) steric parameters, but not Taft’s steric parameters (β-anomers), of the alkyl substituents were observed. The conformational domino effect previously predicted from alkyl β-(1→6)-diglucopyranosides is now supported by the conformational properties of their α-anomers, the anomeric configuration controlling the domino effect. In addition, the rotational populations around the C5′−C6′ bond (torsion angle ω′) depend weakly on the structure of the aglycon and the anomeric configuration.