Sodium hydride → 4-(3,5-Dibenzyloxyphenyl)-1-phenoxypent-3-ene

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Reaction Steps

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 an 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); m/e--450 (m+).

Provenance & Evidence