Advances in the stereoselective synthesis of antifungal agents and ...

Chapter 5 127experiments. But it was interesting to find that the addition of MTBE ascosolvent was a good method to obtain reproducible and homogeneousresults.5.3.4 Enzymatic hydrolysis of (±)-60b in presence of SAMII:effect of the temperature.The last parameter studied was the temperature; here only onesubstrate (±)-60b was used in the experiments (Scheme 5-11.)OAcH OAcHO HSAM IIPH=7; T.+H H HMe Me Me(±)-60b(-)-(S)-60b(-)-(R)-58bScheme 5.11: Effect of the temperaure on the enzymatic hydrolyses of (±)-60b.Entry Substrate T °C Time h Product C % e.e. % E1 (±)60b RT 144 (S)-60b 60.7 100 352 RT (R)-58b 64.83 (±)60b 35 134 (S)-60b 50.4 80.8 224 35 (R)-58b 79.75 (±)60b 55 32 (S)-60b 58.1 89.7 146 55 (R)-58b 64.87 (±)60b 58 19 (S)-60b 51.5 47.3 128 58 (R)-58b 77.0Table5.10: Effect of the temperature on the enzymatic hydrolyses of (±)-60b.Three experiments were carried out at 35°C, 55°C, 58°C. Theresults were compared with those obtained at room temperature, as shownin Tab.5.10.The increased temperature reduced the reaction time butsimultaneously also reduced the E value. Also in this case no improvementover the original results was achieved, but it is important to note that at35°C (±)-60b was an oil in the reaction mixture.