Acetic Acid → 2-Benzyl-1,2,3,4-tetrahydronaphthalen-1-one

Participants

Reaction Steps

4-Fluorobenzyl bromide (20.7 g, 109 mmol) was added to a solution of the enamine in acetonitrile (200 mL) which had been dried over 4A molecular sieves. This mixture was heated at reflux under nitrogen for 3 days. After cooling, the reaction mixture was concentrated in vacuo to provide a brown solid. Chloroform (25 mL), glacial acetic acid (50 mL), and water (200 mL) were added to this material and the resulting mixture was stirred at ambient temperature for 20 h. Additional chloroform was added to the reaction mixture, and the layers were separated. The organic layer was washed with water, dried (Na2SO4), and concentrated to give 24.2 g of the corresponding -benzyl--tetralone as a dark brown oil. This material was purified on a flash silica gel column (25% hexanes-chloroform) to provide 17.9 g of a red oil which was purified further on a flash silica gel column (1:1 hexanes-chloroform) to provide 12.1 g (70%) of desired product, 1-(4-fluorobenzyl)--tetralone, as a yellow oil. MS (CI-CH4), m/z 255 (MH+). 1H NMR (CDCl3) 2.38-2.56 (m, 3H), 2.76-2.86 (m 1H), 3.21 (AB octet, J=15.5, 6.8 Hz, 2H), 3.70 (t, J=6.2 Hz, 1 H), 6.75-6.85 (m, 4H), 6.93 (dd, J=7.5, 2.8 Hz, 1H), 7.09-7.22 (m, 3H).

Provenance & Evidence