反应详情

A suspension of 6.54 g of (methoxymethyl)triphenylphosphonium chloride in 38 ml of abs. THF was cooled to -10° and treated with 11.3 ml of nBuLi (1.5 M, hexane). 15 minutes later, the deep red ylide solution was cooled down to -78° and 3.225 g of (S)-2-[(1R,4aR,5S,8aR)-5-(tert-butyldimethyl-silanyloxy)-8a-methyl-decahydro-naphthalen-1-yl]-propionaldehyde dissolved in 21 ml of abs. THF, were slowly added and the reaction mixture kept for 60 minutes at that temperature. Partition between hexane and EtOH/H2O=8/2, washing of the upper layer with EtOH/H2O=8/2, drying over sodium sulfate, evaporating i. V. and flash chromatography (SiO2, hexane/AcOEt=98/2) delivered 3.11 g of an enolether intermediate as E/Z-mixture, contaminated with some impurities which were removed after the next step. This enolether was hydrolyzed by dissolving it in 35 ml of THF containing 12.5 ml of 25% aq. HCl. After 2.5 h at ambient temperature, the reaction mixture was poured onto crushed ice, extracted with ether, washed with water and brine, dried over sodium sulfate and evaporated to dryness. Flash chromatography (SiO2, hexane/AcOEt=98/2) yielded 1.76 g of (R)-3-[(1R,4aR,5S,8aR)-5-(tert-butyldimethyl-silanyloxy)-8a-methyl-decahydro-naphthalen-1-yl]-butyraldehyde as colourless oil.

1. temperature15 minutes later, the deep red ylide solution was cooled down to -78°
2. customPartition between hexane and EtOH/H2O=8/2
3. washwashing of the upper layer with EtOH/H2O=8/2
4. dry with materialdrying over sodium sulfate
5. customevaporating i
6. customwere removed after the next step
7. dissolutionby dissolving it in 35 ml of THF containing 12.5 ml of 25% aq. HCl
8. waitAfter 2.5 h at ambient temperature
9. additionthe reaction mixture was poured
10. customonto crushed ice
11. extractionextracted with ether
12. washwashed with water and brine
13. dry with materialdried over sodium sulfate
14. customevaporated to dryness