反应详情

71.6 mg of lithium chloride was suspended in 5 ml of dry THF under an argon atmosphere, and 426 mg of ethyl 2-diethylphosphonobutanoate dissolved in 0.6 ml of dry THF was added thereto under stirring. The mixture was stirred at room temperature for 5 minutes, and then 323 mg of 1,8-diazabicyclo[5,4,0]-7-undecene (hereinafter referred to simply as DBU) was added thereto in the form of a 50% dry THF solution, and the mixture was stirred at room temperature for 10 minutes. Then, 450 mg of (4S,5R)-3-benzyloxycarbonyl-2,2-dimethyl-5-formyl-4-isobutyloxazolidine dissolved in 1.0 ml of dry THF was added thereto, and the mixture was stirred at room temperature overnight. The reaction solution was cooled to 0° C. and neutralized with 1N hydrochloric acid. Then, the solution was extracted three times with ethyl acetate. The organic layer was washed with water and with a saturated sodium chloride aqueous solution and dried over anhydrous sodium sulfate. The solvent was distilled off under reduced pressure, and the residue was purified by silica gel column chromatography (n-hexane/ethyl acetate=10/1) to obtain 518 mg of ethyl 3-[(4S,5S)-3-benzyloxycarbonyl-2,2-dimethyl-4-isobutyloxazolidin-5-yl]-2-ethyl-2-propenoate as colorless oily substance.

1. additionwas added
2. stirringThe mixture was stirred at room temperature for 5 minutes
3. additionwas added
4. additionwas added
5. stirringthe mixture was stirred at room temperature overnight
6. extractionThen, the solution was extracted three times with ethyl acetate
7. washThe organic layer was washed with water and with a saturated sodium chloride aqueous solution
8. dry with materialdried over anhydrous sodium sulfate
9. distillationThe solvent was distilled off under reduced pressure
10. customthe residue was purified by silica gel column chromatography (n-hexane/ethyl acetate=10/1)