488714-55-2Relevant academic research and scientific papers
Imidazole-promoted 1,4-migration of the tert-butyldiphenylsilyl group: Influence on the selectivity control of the silylation reactions of carbohydrate OH groups
Arias-Perez, Maria Selma,Lopez, Maria Soledad,Santos, Maria Jesus
, p. 1549 - 1552 (2007/10/03)
The regioselective protection of secondary hydroxy groups of gluco-, galacto-, manno-, rhamno- and fucopyranosides using TBDPSCl with imidazole in DMF has been studied. It was found that the relative spatial arrangement of the OH groups modulates the silylation selectivity which arises from the combination of kinetic factors and the intramolecular migrations of the secondary TBDPS groups. The rearrangement of the TBDPS groups has a much larger effect on the α-D-manno- and α-L-rhamnopyranosides, allowing the protection of the OH groups at positions 2, 3 or 2 and 4, in synthetically useful yields, by changing the reaction conditions. The relative reactivity of the secondary OH groups seems particularly likely to be governed by steric factors. This trend provides a valuable approach to the synthesis of 3-O-tert-butyldiphenylsilyl-1-thio-β-L-fucopyranoside.
Stereochemical study of the CD spectral differences between anomers of alkyl glucopyranosides
Padron, Juan I.,Vazquez, Jesus T.
, p. 613 - 627 (2007/10/03)
Slightly different chair conformation geometries were demonstrated to be the origin of the C-D spectral differences observed in anomers of alkyl glucopyranosides. The study, using methyl glucopyranoside derivatives as model compounds, showed excellent agreement between CD data, 1H NMR data, and semiempirical calculations, and the geometries found explained satisfactorily the higher amplitudes observed for the β-anomers of tetrachromophorically substituted alkyl glucopyranosides. The pairwise interactions involving the chromophore at C2, the 2/3, 2/4 and 2/6, were the most dependent on the anomeric configuration, the 2/4 interaction even showing opposite CD signs for the anomers. In addition, the 2/3 pairwise interaction was revealed to be independent of the structural nature of the aglycon.
