Phosphorus oxychloride → 6-Methoxy-1-methyl-3,4-dihydro-2-naphthaldehyde

Participants

Reaction Conditions

Reaction Steps

To a solution of Compound B (0.44 g, 2.5 mmole) in dry dimethylfomamide (1.3 ml, 16.8 mmole) at ice cooling and stirring under argon atmosphere, phosphorus oxychloride (0.62 ml, 6.65 mmole) was added drop-by-drop in 2 minutes. The reaction mixture was stirred in an oil bath of 70-75° C. for 3 hours. After cooling in an ice bath, ice (6 g) was added, then sodium acetate (anhydrous, 3.7 g) was added, and the mixture (pH 6) was warmed in an oil bath at 70-75° C. for 15 minutes. After cooling, it was extracted with ether (1×10 ml and 3×5 ml), the combined organic solutions were washed with water (3×3 ml), dried (magnesium sulfate), decolorized (with activated carbon), and evaporated. The residue (0.33 g) was recrystallized from cyclohexane (2 ml) and dried over potassium hydroxide in a vacuum giving the pure product 6-Methoxy-1-methyl-3,4-dihydro-2-naphthaldehyde (Compound C, 0.22 g, 44%) as light brown crystals, mp. 70-72° C.

Provenance & Evidence