Biocatalytic synthesis of (-)-1-trimethylsilylethanol by asymmetric reduction of acetyltrimethylsilane with a new isolate Rhodotorula Sp.aS2.2241

摘要

A new isolate,Rhodotorular sp.AS2.2241,capable ofreducing acetophenone and alphe-bromoacetophenone with high stereoselectivity,was further studied to exploit its potential in the asymmetric reduction of sillicon-containing ketones to sillyl alcohols. After encapsulation,the cells were used in an aqueous or an aqueous/organic solvent biphasic system for the asymmetric reducition of acetyltrimethysilane (ATMS) to prepare (-)-1-trimethylsilylethanol[(-)-TMSE]. It has been found that higher product yield and product enantiomeric excess could be achieved wiht immobilized cells in an aqueous/roganic solvent biphasic system. For optimization of the reaction,various influentila variables,such as the volume ratio of the aqueous phase to the organic phase,the hydrophobicity of the organic solvent,reactiontemperature,buffer pH of the aquous phase and the shaking speed,were examined with respect to the initial reaction rate,the product yield and the enantiomeric excess (e.e.)of TMSE formed. All the factors mentioned above had influences on the reaction to some extent.Isooctane was found to be the most suitable organic phase for the reaction. The optimum volume ratio of the aqueous phase to the organic phase,reaction temperature,buffer pH and shking speed were 1/1,40 deg C,6.5 and 150 rpm,respectively under which the product yield and the product enantiomeric excess were as high as 99 and 90%,which are much higher than those preoviously obtained by enantioselective reduction of acylsilanes.