Hydrochloric Acid → ethyl 3-[(4S,5S)-3-benzyloxycarbonyl-2,2-dimethyl-4-isobutyloxazolidin-5-yl]-2-ethyl-2-propenoate

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反応手順

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.

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