Hydrochloric Acid → Diethyl (E)-4-[2-(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl2-naphthyl)-1-ethenyl]-benzenephosphonate

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Reaction Steps

A solution of 22 g (53 millimoles) of diethyl 4diethylphosphonomethylbenzenephosphonate in 100 ml of dimethyl sulfoxide was added dropwise to a suspension of 1.8 g (64 millimoles) of sodium hydride in 50 ml of dry dimethyl sulfoxide at room temperature. Stirring was continued for 1 hour, after which a solution of 8.7 g (40 millimoles) of 2-formyl-5,6,7,8-tetrahydro-5,5,8,8-tetramethylnaphthalene in 75 ml of dimethyl sulfoxide was added dropwise. Stirring was continued for 16 hours at room temperature and the mixture was poured onto water, acidified with 2N hydrochloric acid and extracted three times with ether. The combined organic phases were washed twice with water and twice with saturated sodium chloride solution, dried over sodium sulfate and evaporated down. The residue was purified by column chromatography (silica gel; heptane/0.55 - 10% ethyl acetate) to give 5.5 g of the title compound of melting point 83°-84° C.

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