Acetyl chloride → 1-(2,2,4,4-Tetramethyl-3,4-dihydro-2H-1-benzopyran-6-yl)ethan-1-one

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Reaction Steps

To an ice bath cooled solution of 2 g (10.53 mmol) of 2,2,4,4-tetramethylchroman (Compound 4o) in 25 ml of nitromethane was added, under nitrogen, 941 mg 11.99 mmol) of acetyl chloride followed by 1.59 g (11.92) mmol) of aluminum chloride. The cooling bath was then removed and the mixture stirred at room temperature for 16 h. The mixture was then cooled again in an ice bath and treated with 25 ml of conc. HCl. The mixture was then filtered and the residue washed with methylene chloride. The filtrate was concentrated in vacuo and the resultant residue was purified by flash chromatography (silica; 10% ethyl acetate in hexanes) to give the title compound as a yellow oil. PMR (CDCl3): & 1.38 (6H, s), 1.39 (6H, s), 1.87 (2H, s), 2.56 (3H, s), 6.83 (1H, d, J~8.7 Hz), 7.71 (1H, dd, J~8.7 Hz, 2.1 Hz), 7.98 (1H, d, J~2.1 Hz). MS exact mass, m/e 232.1468 (calcd. for C13H20O2 , 232.1464).

Provenance & Evidence