CGC, MS and theoretical studies on the transformation mechanism of 3,4-di-O-acetyl-1,5-anhydro-2-deoxy-D-threo-pent-1-enitol in aqueous solutions

Abstract

Heating 3,4-di-O-acetyl-1,5-anhydro-2-deoxy-D-threo-pent-1-enitol (per-O-acetyl-D-xylal) in water leads to a mixture of unsaturated compounds with cyclic, as well as open-chain structures. The mixture obtained was analysed by CGC and CGC–MS methods. The experimental findings were employed to model the mechanism of the transformation studied. In addition, the AM1 calculations were carried out in order to describe the elementary processes suggested. Full geometry optimizations performed for species found in the mixture made it possible to evaluate the thermodynamic characteristics of particular reactions. Next, the calculations for transition states afforded appropriate kinetic barriers. All computations were carried out for the gaseous phase as well as in aqueous solution. Both experimental and theoretical results are in good accordance with the mechanism proposed.