Ammonia → (4-Prop-2-ynylcyclohexyl)methanol

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

A 3-neck 250 mL-flask equipped with a gas inlet tube and dry-ice condenser was cooled to −78° C. and charged with liquid ammonia (40 mL). To the reaction mixture was added lithium wire (600 mg, 86.4 mmol) generating a deep blue solution. The mixture was allowed to stir for 1 hour. Acetylene, passed through a charcoal drying tube, was added to the ammonia until all the lithium had reacted and the solution turned colorless, at which time the flow of acetylene was stopped, the acetylene-inlet tube and condenser removed and the flask outfitted with a thermometer. DMSO (20 mL) was added and the ammonia evaporated with a warm water bath until the mixture reached a temperature of 30° C. The solution was stirred at this temperature for 2 hours until the solution stopped bubbling. The mixture was cooled to 5° C. and compound 84 (11.25 g, 27.3 mmol), in DMSO (10 mL), was added. The temperature was maintained at 5° C. The mixture was allowed to stir at 5° C. for 0.5 hours. Then the solution was gradually warmed to room temperature and stirred for an additional 18 hours. The brown/black reaction mixture was poured slowly over ice (300 g) and extracted with ether (4×100 mL), dried with anhydrous sodium sulfate, and concentrated in vacuo to yield a yellow oil. The oil was subsequently dissolved in THF (200 mL) and changed to a brownish color upon addition of TBAF hydrate (11.20 g, 35.5 mmol). The solution was allowed to stir for 24 hours under N2 atmosphere. After stirring, the reaction was quenched with water (200 mL) and extracted with ether (3×100 mL). The ether extracts were combined and concentrated in vacuo. The crude product was purified by chromatography, on a silica gel column, eluting with 1:1 ether/petroleum ether to yield 86 (3.91 g, 93%) as a yellow oil. 1H NMR (CDCl3) δ 3.45 (d, J=6.2, 2H), 2.10 (d, J=6.2, 2H), 1.9 (s, 1H), 1.94–1.69 (m, 4H), 1.52–1.34 (m, 2H), 1.16 –0.83 (m, 4H); 13C NMR (CDCl3) δ 83.8, 69.5, 69.0, 40.8, 37.7, 32.3, 29.7, 26.5.

Herkunft & Nachweise