BACKGROUND: The response surface methodology was successfully applied to the optimization of the reaction variables for the kinetic resolution of a precursor of high-value myo-inositols, ( ± )-1,2-O-isopropylidene-3,6-di-O-benzyl-myo-inositol (( ± )-1), by Novozym 435. The resolutions were run separately, with two acylating agents, ethyl acetate and vinyl acetate, in a solvent-free system. The variables analyzed were reaction temperature, substrate concentration, water concentration and enzyme activity. A statistical model was employed for the evaluation of the influence of the variables on conversion and enantiomeric excess (ee).
RESULTS: The optimal conditions for this resolution using vinyl acetate as acylating agent were 45 °C, 5 mg mL−1 of substrate, 71 U of enzyme activity and 0%w/w of water concentration. The high conversion (49.2 %) and ee (>99%) reached in the chemoenzymatic synthesis of acylated product, L-(−)-5-O-Acetyl-3,6-di-O-benzyl-1,2-O-isopropylidene-myo-inositol, secure the efficient synthesis of the D enantiomorph present in the original racemic mixture (( ± )-1) as well.
CONCLUSIONS: The use of the experimental design strategy was productive, leading to a 14-fold increase in the productivity of the reaction compared with the non-optimized conditions. Both derivative L-(−)-2 and remaining substrate D-(+)-1 were obtained at high ee. © 2012 Society of Chemical Industry