反应详情

A solution of n-butyl lithium in hexane (119 ml, 1.6M, 0.19 mol) is added dropwise to a solution of diisopropylamine (19.3 g, 0.191 mol) in THF (100 ml) cooled in an ice bath. After the additiion, the mixture is stirred for 20 minutes then cooled to -78°. A solution of 6-t-butyldimethylsilyloxy-hexan-2-one (40.0 g, 0.174 mol) in THF is added dropwise. The resultant mixture is stirred for 90 minutes then a solution of 2,2-dimethyl-1,3-dioxolane-4-acetaldehyde (25.1 g, 0.174 mol) in THF (100 ml) is added dropwise. After the addition, the mixture is stirred for 2 hours, then water (10 ml) slowly added. The mixture is warmed to 0°, diluted with water (300 ml) and extracted with ether (2×500 ml). The extracts are washed with saturated brine, dried over sodium sulfate and concentrated under reduced pressure to leave the crude product (63.5 g) an oil. A portion of this material (46 g) is chromatographed on silica gel (2.5 Kg) eluting with 25% ethyl acetate/hexane to give the title compound, 8-t-butyldimethylsilyloxy-1-(2,2-dimethyl-1,3-doxolan-4-yl)-2-hydroxyoctan-4-one; (23 g, 49%) an oil.

1. temperaturecooled in an ice bath
2. temperaturethen cooled to -78°
3. additionAfter the addition
4. stirringthe mixture is stirred for 2 hours
5. temperatureThe mixture is warmed to 0°
6. extractionextracted with ether (2×500 ml)
7. washThe extracts are washed with saturated brine
8. dry with materialdried over sodium sulfate
9. concentrationconcentrated under reduced pressure
10. customto leave the crude product (63.5 g) an oil
11. customA portion of this material (46 g) is chromatographed on silica gel (2.5 Kg)
12. washeluting with 25% ethyl acetate/hexane