2-Cyclohexen-1-one, 3-ethoxy-5,5-dimethyl- → 2-Cyclohexenone, 5,5-dimethyl-

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Reaction Steps

To a flame-dried 100 mL round-bottomed flask containing lithium aluminum hydride (0.95 g, 24.4 mmol, 0.5 mol equiv) in 35 mL anhydrous ether under nitrogen atmosphere at 0° C. was added 8.20 g (48.7 mmol) 3-ethoxy-5,5-dimethylcyclohex-2-en-l-one (10) portionwise through a syringe as a solution in 10 mL anhydrous ether. The reaction mixture was allowed to warm to room temperature, and after 4h, TLC. analysis indicated complete consumption of starting material. The reaction mixture was then cooled to 0° C. before the cautious addition of 50 mL water, and the contents of the flask were then poured into a 500 mL Edenmeyer flask containing 150 mL ice-cold 10% H2SO4. The mixture was then extracted with ether (2×200 mL), and the combined organics were washed successively with water (100 mL), and saturated aqueous NaHCO3 (100 mL), dried over Na2SO4, and concentrated under diminished pressure to give 6.05 g (quantitative) of the dimethylenone (Rf 0.55, 2:1 hexane/ethyl acetate). 1H NMR (400 MHz, CDCl3) δ1.05 (s, 6H, geminal-CH3 's), 2.23 (dd, 2H, 4-H), 2.28 (s, 2H, 6-H), 6.03 (ddd, 1H, 2-H), 6.87 ppm (ddd, 1H, 3-H). ##STR5##

Provenance & Evidence