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

Chapter 8 174carried out in a thermostated reactor. The reaction mixtures were stirredat the desired temperature and monitored by chiral GC. The analysis wasquantitative and allowed the determination of conversion and theenantiomeric excess of both product and starting material from the singlechromatogram.See chapter 5, table 5.10 for substrates and products, chemical yields,conversions and E-values and temperatures.8.27 Synthesis of 1-aryl-2-propyn-1-ol chloroacetate (±)-61:To a solution of aryl propynol (±)58 (10 mmol) and triethylamine(11 mmol) in dichloromethane (40 ml) at 0°C, chloroacetic anhydride(10.5 mmol) was added dropwise over 30 min. The mixture was stirredfor 1 h at room temperature, then diluted with CH 2 Cl 2 and washedconsecutively with 1 N HCl solution, saturated NaCl solution and finallydried over anhydrous Na 2 SO 4. The crude product was so clean thatanother purification was unnecessary.See chapter 5, table 5.11 for substrates, products and chemical yields.8.28 Enzymatic resolution of chloroacetates (±)-61 b-c,e,h-l:8.28.1 General procedure:Chloroacetate (±)-61 (10 mmol)was suspended in 0.1 N phosphatebuffer (10 ml, pH=7.0) and the mixture was stirred 10 min.on theautotitrator in order to test for non-catalyzed hydrolysis. Then the crudelipase preparation of Pseudomonas species (SAMII) was added (10% byweight of the ester). The reaction mixture was stirred at roomtemperature, while the pH of the reaction was kept at pH 7.0 bycontinuous addition of 1 N NaOH from an autoburette. The reactionprogress was monitored by chiral GC allowing simultaneousdetermination of conversion and enantiomeric purities of both educt andproduct. After the desired or required conversion was achieved thereaction mixture was diluted with water and diethyl ether and theresulting phases were separated. The organic phase was washed withwater and saturated NaCl solution and finally was dried over anhydrous