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

Chapter 8 176solution and finally dried over anhydrous Na 2 SO 4 . After solventevaporation the crude oil was purified by flash chromatography on silicagel to afford (±)-27g in 91% chemical yield.The experimental procedure described above was applied also to theracemic and enantiopure aryl propynols 58a-c,e,h-l. See chapter 6, table6.5.for reaction times, chemical yields and enantiomeric purities.8.31 Synthesis of aryl benzo[b]furan carbinol by basecatalyzed 5-endotrig cyclization8.31.1 Synthesis of phenyl-2benzo[b]furanyl carbinol (±)-27gby base catalyzed 5-endotrig cyclization:(2'-Hydroxyphenyl)-2-propyne-1-phenyl-1-ol (±)-62 (224 mg, 1mmol) was dissolved in 2 ml of saturated K 2 CO 3 solution in methanol.After two hours the reaction was completed. Methanol was evaporatedand the crude product dissolved in ethylacetate. The solution was washedwith water and saturated solution of sodium chloride and finally driedover anhydrous Na 2 SO 4 . The solvent was evaporated and the crudeproduct was filtered through a silica gel pad to afford phenyl-2benzo[b]furanyl carbinol (±)-27g in 92% yield. All spectroscopic datawere identical with those obtained via other routes.8.31.2 Cyclization of 1-phenyl-3-(2'acetoxyphenyl)-2-propyn-1-ol (±)71 to phenyl-2benzo[b]furanyl carbinol (±)-2 bybasic catalyzed 5-endotrig cyclization.1-phenyl-3-(2'-acetoxyphenyl)-2-propyn-1-ol (±)-71 (265 mg,1mmol) was dissolved in 5 ml of a saturated solution of K 2 CO 3 inmethanol at 0°C. After one hour the TLC showed complete consumptionof the starting material. The methanol was evaporated, and the resultingoil dissolved in ethylacetate and water. The organic phase was separatedand washed with saturated NaCl solution, and was finally dried overanhydrous Na 2 SO4. After evaporation of the solvent (±)-27g wasobtained in 95.0% chemical yield.