反应详情

Under a nitrogen atmosphere a mixture of 3,5-dibenzyloxyacetophenone (50.0 g., 0.15 M) in tetrahydrofuran (175 ml.) and 3-phenoxypropyltriphenylphosphonium bromide (7.18 g., 0.15 M) in dimethylsulfoxide (450 ml.) is added dropwise over 1.75 hours to a suspension of 50% sodium hydride (7.89 g., 0.165 M) (previously washed with pentane) in tetrahydrofuran (75 ml.) maintained at 0°-5° C. After stirring for 4 hours at 0°-5° C. the reaction is allowed to warm to room temperature and is then carefully stirred into ice water (2000 ml.), acidified with concentrated hydrochloric acid, and extracted with ethyl acetate (5×400 ml.). The combined organic phases are washed with saturated sodium chloride solution (3×300 ml.), dried over sodium sulfate and concentrated under vacuum to yield an oil which is triturated with ether to precipitate triphenylphosphine oxide. Filtration, followed by concentration of the filtrate, gives as oily residue which is chromatographed over silica gel (1300 g.) eluting with benzene-hexane consisting of 30% to 100% benzene. From the middle fractions 51 g. (75%) of 4-(3,5-dibenzyloxyphenyl)-1-phenoxypent-3-ene is isolated as an oil; Rf =0.8 (silica gel, 2-benzene:1-hexane); MS (mol.ion): 450.

1. washpreviously washed with pentane) in tetrahydrofuran (75 ml.)
2. temperaturemaintained at 0°-5° C
3. stirringis then carefully stirred into ice water (2000 ml.)
4. extractionextracted with ethyl acetate (5×400 ml.)
5. washThe combined organic phases are washed with saturated sodium chloride solution (3×300 ml.)
6. dry with materialdried over sodium sulfate
7. concentrationconcentrated under vacuum
8. customto yield an oil which
9. customis triturated with ether
10. customto precipitate triphenylphosphine oxide
11. filtrationFiltration
12. customgives as oily residue which
13. customis chromatographed over silica gel (1300 g.)
14. washeluting with benzene-hexane