反应详情

To a −78° C. cold 2 M solution of lithium diisopropylamide (305 mmol) in THF/n-heptane (152.4 ml) was added a solution of ethoxy-acetic acid ethyl ester (45.2 ml, 331 mmol) in tetrahydrofuran (240 ml) within 1.5 h under an argon atmosphere. The mixture was stirred for 30 min. A solution of 4-benzyloxy-2-methyl-benzaldehyde (30 g, 132.6 mmol) in tetrahydrofuran (420 ml) was added dropwise over a period of 50 min. The reaction mixture was stirred 2 h at −78° C., poured onto ice water/aqueous ammonium chloride solution 1/1 and extracted two times with ethyl acetate. The combined extracts were washed three times with ice water/brine 1/1 and dried over sodium sulfate. The solvent was removed under reduced pressure and the residue purified by column chromatography (silica gel, n-heptane/AcOEt) to give 48.8 g (136.2 mmol) of the title compound as a mixture of stereoisomers as yellow oil.

1. stirringThe reaction mixture was stirred 2 h at −78° C.
2. additionpoured onto ice water/aqueous ammonium chloride solution 1/1
3. extractionextracted two times with ethyl acetate
4. washThe combined extracts were washed three times with ice water/brine 1/1
5. dry with materialdried over sodium sulfate
6. customThe solvent was removed under reduced pressure
7. customthe residue purified by column chromatography (silica gel, n-heptane/AcOEt)