Tetrahydrofuran → 2-Octen-4-one, 2-methyl-

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Reaction Steps

To a magnetically stirred and ice-cooled solution of N-methoxy-N-methyl-acrylamide (20 gram, 132.7 mmol) in anhydrous tetrahydrofuran (200 ml) in a nitrogen atmosphere was slowly added n-butylmagnesium chloride (132.7 ml, 2 M solution in diethyl ether, 265 mmol) and the resulting mixture was stirred for 30 minutes. The resulting mixture was allowed to attain room temperature and stirred for 40 hours. An aqueous ammonium chloride solution (15 gram dissolved in 100 ml water) was slowly added, followed by addition of ethyl acetate (100 ml). The organic layer was separated, washed with brine, dried over MgSO4, filtered and concentrated in vacuo to give crude 2-methyl-oct-2-en-4-one. Sepacore (80×150 mm column) separation (eluant: petroleum ether (40-60)/diethyl ether=95/5 (v/v)) gave 2-methyl-oct-2-en-4-one (Intermediate IIIb-1) as a colorless oil (9.30 gram, 47% yield). 1H-NMR (400 MHz, CDCl3) δ 0.91 (t, J=7.2 Hz, 3H), 1.27-1.38 (M, 2H), 1.52-1.62 (m, 2H), 1.89 (s, 3H), 2.14 (s, 3H), 2.39 (t, J=7.4 Hz, 2H), 6.08 (br s, 1H).

Provenance & Evidence