Phosphorus oxide (P4O10) → 2-cyclopentyl-7-methoxy-3,4-dihydroisoquinolin-1(2H)-one

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Reaction Steps

To a solution of methyl cyclopentyl(4-methoxyphenethyl)carbamate (0.830 g, 3 mmol) in POCl3 (10 mL) was added P2O5 (0.852, 6 mmol). The reaction mixture was heated at reflux for 2 h. Excess POCl3 was removed under reduced pressure and quenched with ice water. The mixture was neutralized with Na2CO3, extracted with ethyl acetate and dried over Na2SO4. Concentration of the solvent followed by chromatographic separation (silica gel, 30% EtOAc:Hexanes) afforded 2-cyclopentyl-7-methoxy-3,4-dihydroisoquinolin-1(2H)-one (0.698 g, 95%). 1HNMR (400 MHz, CDCl3): δ 7.60 (s, 1H), 7.05 (d, 1H, J=8.6 Hz), 6.93 (d, 111, J=8.6 Hz), 5.19-5.15 (m, 1H), 3.83 (s, 3H), 3.40 (t, 211, J=6.1 Hz), 2.85 (t, 2H, J=6.1 Hz), 1.90-1.89 (m, 2H), 1.72-1.53 (m, 6H). LC-MS (ESI) Calcd for C15H19NO2 [M+H]+: 246.14. Found: 246.00.

Provenance & Evidence