反应详情

A solution of 2.5 g of 2-fluoro-3-octyloxybenzaldehyde (prepared by reacting 2-octyloxyfluorobenzene with lithium diisopropylamide followed by reaction with N,N-dimethylformamide) in 50 ml of THF is added dropwise at 20° C. to a fully reacted mixture of 5.6 g of 2-fluoro-3-octyloxybenzyltriphenylphosphoniumbromide (prepared by the reaction sequence: reaction of 2-fluoro-3-octyloxybenzaldehyde with LiAlH4 in THF to give fluoro-3-octyloxybenzyl alcohol, reaction of the latter with triphenylphosphine/Br2 to give 2-fluoro-3-octyloxybenzyl bromide and reaction of the latter with triphenylphosphine in toluene) and 1.2 g of potassium tert-butoxide in 100 ml of THF. When the reaction is complete, the mixture is adjusted to pH 5 using HCl, 500 ml of H2O are added, and the mixture is extracted three times with 100 ml of diethyl ether in each case. Chromatography on silica gel using dichloromethane/heptane 1:1 gives 1,2-bis(2-fluoro-3-octyloxyphenyl)ethene as an E/Z-mixture. The latter is dissolved in cyclohexane, 4 mol % of iodine are added, and the mixture is exposed to UV light for 8 hours at 25° C. in a quartz apparatus. Chromatography on SiO2 using dichloromethane and recrystallization from acetonitrile give 1.2 g of 1,8-difluoro-2,7-dioctyloxyphenanthrene as colorless crystals.

1. customprepared by the reaction sequence
2. customto give
3. customto give
4. additionare added
5. extractionthe mixture is extracted three times with 100 ml of diethyl ether in each case