Phosphorus oxide (P4O10) → 2-Methoxy-6,7,8,9-tetrahydro-benzocyclohepten-5-one

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Reaction Conditions

Reaction Steps

To a homogeneous mixture of phosphorus pentoxide and 85% phosphorus acid at 100° C., was added 5-(3-methoxyphenyl)pentanoic acid in small portions over 20 minutes. The vigorously stirred mixture was heated at 100° C. for 6 hours. Then it was poured on ice-water, and extracted with ether (3 times). The organic phase was washed with water and dried over anhydrous sodium sulfate. Evaporation of the combined organic phase afforded a light yellow oil in more than 95% yield; 1H NMR δ 7.77 (d, 1H, J=8.6 Hz), 6.80 (dd, 1H, J=2.5, 8.6 Hz), 6.69 (d, 1H, J=2.5 Hz), 3.84 (s, 3H), 2.90 (t, 2H, J=6.2 Hz), 2.71 (t, 2H, J=5.9 Hz), 1.91-1.76 (m, 4H).

Provenance & Evidence