Hydrochloric Acid → 1-Cyclohexyl-1-hydroxy-1-phenyl-7-bromohept-5-yn-2-one

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

To a dry flask under argon was added 1,1,1,3,3,3-hexamethyldisilazane (11.6 g, 71.6 mmole) and 75 ml of THF. The solution was cooled to -10° C. and n-BuLi (19.8 g, 71.3 mmol) was added directly to the reaction mixture. The solution was stirred at -10° C. for 30 minutes. A solution of 1-cyclohexyl-1-phenyl-1-trimethylsilyloxypropan-2-one (21.99 g, 72.2 mmol) in dry THF (75 ml) was added dropwise over a period of 15 minutes and the reaction mixture was stirred at -10° C. After the solution had stirred for 1 hour 1,4-dibromo-2-butyne (59.9 g, 0.3 mole) was added directly to the reaction mixture and the mixture was stirred an additional hour. The reaction was stopped by the dropwise addition of a solution of glacial acetic acid (7 ml) in ether (20 ml). The solution was warmed to room temperature and ether (150 ml) was added. The solution was washed with water followed by a saturated aqueous sodium chloride solution. The ether layer was dried and concentrated to afford a brownish liquid. This oil was dissolved in 150 ml of methanol and 0.2 ml of concentrated hydrochloric acid was added. The solution was stirred at 40° C. for 30 minutes and cooled to room temperature. Water was then added until the solution became cloudy and then 150 ml of ether was added. The solution was washed with a saturated aqueous sodium chloride solution, dried over sodium sulfate, and evaporated under vacuum to afford a yellowish brown oil. Purification on a silica column with a hexane:ethyl acetate solution (98:2 followed by 9:1) afforded an orange oil (16.1 g, 59.5%). NMR (CDCl3) δ7.6-7.2(m, 5H), 4.3(s, 1H), 3.8(t, 2H), 2.8-2.6 (m, 2H), 2.5-2.3(m, 2H), 1.9-1.1(m, 11H). IR (neat) 3461, 2234, 1705, 609 cm-1. TLC (silica, petroleum ether:ethyl acetate (95:5)) Rf=0.53.

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