反应详情

To a solution of 2-bromo-5-trifluoromethyl benzonitrile (20.16 mmoles) in methylene chloride (50 ml), under argon at room temperature, was added diisobutylaluminum hydride (25 mmoles, 25 ml hexane) dropwise and the resulting solution was stirred for 30 minutes. The reaction mixture was diluted with ether (50 ml), cooled in ice and quenched by the careful addition of hydrochloric acid (50 ml, 3 N). The ice bath was removed and the mixture was stirred vigorously for 15 minutes. The organic layer was washed with brine (50 ml), treated with magnesium sulfate-charcoal and evaporated. The resulting oil was purified by distillation to give 2-bromo-5-trifluoromethyl benzaldehyde, bp 50°-55° C. at 0.05 mm Hg. A mixture of this compound (16.24 mmoles), 1-phenylocta-1,7-diyne (19.54 mmoles, prepared as in Example 7b), cuprous iodide (0.19 mmoles) and bis(triphenylphosphine) palladium chloride (0.34 mmoles) in triethylamine (50 ml) was refluxed under argon for 30 minutes. The reaction mixture was cooled and filtered. The filtrate was evaporated, taken up in ether (100 ml), washed with hydrochloric acid (50 ml, 3 N) and sodium chloride, and treated with magnesium sulfate-charcoal. Filtration and evaporation left an oil which was purified by flash chromatography (5% ether/hexane) to yield 2-(8-phenyloctadiyn-1,7-yl)-5-trifluoromethyl benzaldehyde as an oil. A solution of this compound (13.26 mmoles) in ethyl acetate (100 ml) was treated with charcoal for 30 minutes and then filtered. The solution was then shaken under 50 psi of hydrogen with 10% palladium on charcoal (502 mg) for about 90 minutes. Thin layer chromatography of the reaction mixture indicated about 50% reduction of the aldehyde to the alcohol. To re-oxidize the alcohol, the palladium catalyst was filtered off and manganese dioxide (20 g) was added. This mixture was then stirred at room temperature under argon for 18 hours. Filtration and evaporation gave an oil which was purified by flash chromatography (2% ether/hexane) to afford 2-(8-phenyloctyl)-5-trifluoromethyl benzaldehyde as an oil.

1. temperaturecooled in ice
2. customquenched by the careful addition of hydrochloric acid (50 ml, 3 N)
3. customThe ice bath was removed
4. stirringthe mixture was stirred vigorously for 15 minutes
5. washThe organic layer was washed with brine (50 ml)
6. additiontreated with magnesium sulfate-charcoal
7. customevaporated
8. distillationThe resulting oil was purified by distillation