Study of Cyclization of Diphenylacetals Derived from L-rhamnose and L-fucose: A Theoretical Approach

This work aimed to study the configuration of two mono-tosyl-diphenylacetals, highly flexible molecules derived from L-ramnose and L-fucose, by means of the Monte Carlo conformational search method. The energy of the conformers established by this method and calculated by using the molecular mechanics force field (MMFF) permitted to establish a first conformational space. The geometry of the conformers was optimized by using the semi-empirical AM1 and the density functional B3LYP/DGDZVP methods. We were able to explain the different final products recovered from the reaction of the diphenylacetals derived from L-rhamnose and L-fucose with tosyl chloride, in a pyridine solution. On the other hand, obtaining cyclical compounds by intramolecular cyclization could be an attractive pathway for the synthesis of furanosides.Keywords: Molecular modelling, conformational analysis, Monte Carlo conformational search method, L-rhamnose, L-fucose, B3LYP, DGDZVP, diphenylthioaceta