Optimisation, scope and advantages of the synthesis of chiral phenylethanols using whole seeds ofBauhinia variegataL. (Fabaceae) as a new and stereoselective bio-reducer of carbonyl compounds

摘要

With the aim of finding new methods for environmentally friendly synthesis of chiral phenylethanols, a screening was carried out to identify seeds that could be used as a biocatalyst capable of reducing stereoselectively prochiral ketones. As a result, seeds ofBauhinia variegataL. (Fabaceae) were identified as being an efficient and stereoselective biological reducer of acetophenone to produce (S)-1-phenylethanol (conversion of 98 and 99e.e.). Then, to optimise the reductive process, the effects of some variables such as temperature, load of substrate, pH, co-solvent, and reuse and storability of the seeds as a function of time were established. Utilising the optimal reaction conditions, nineteen substituted acetophenones were reduced to their corresponding chiral alcohols with a conversion ranging from 30 to 98 and enantiomeric excess of between 65 and >99, and in addition, useful key intermediates were also obtained by the synthesis of drugs. The scope and advantages of this new biocatalytic synthetic method are also discussed.