Ethyl 4-formylbenzoate → Ethyl p-[2-(4,5,6,7-tetrahydro-4,4,7,7-tetramethylbenzo[b]thien-2-yl)propenyl]-benzoate

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Reaction Steps

30 g of [1-(4,5,6,7-tetrahydro-4,4,7,7-tetramethylbenzo[b]thien-2-yl)ethyl]triphenylphosphonium bromide and 9.5 g of 4-ethoxycarbonylbenzaldehyde are suspended in 300 ml of butylene oxide and the mixture is heated at reflux for 4 hours. The thus-obtained solution is concentrated to one third of the original volume in a water-jet vacuum, poured into 500 ml of a methanol/water mixture (6:4) and extracted several times with hexane. The organic phase is washed three times with water, dried over sodium sulphate and evaporated. There is obtained a light brownish oil which is purified by filtration over silica gel (eluting agent hexane/ether 19:1). After recrystallization from hexane, there are obtained 11.3 g of ethyl p-[2-(4,5,6,7-tetrahydro-4,4,7,7-tetramethylbenzo[b]thien-2-yl)propenyl]-benzoate in the form of colorless crystals, m.p. 118°-120° C.

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