5-Methoxytetralone → 5-Methoxy-1-methylene-1,2,3,4-tetrahydronaphthalene

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Reaction Steps

To a slurry of 5-Methoxy-3,4-dihydro-2H-naphthalen-1-one (25 g, 0.14 mol) and methyltriphenylphosphonium iodide (1.13 eq) in THF (250 mL) at RT was added potassium t-butoxide (1.6 eq) at such a rate as to maintain a temperature no higher than warm to the touch. The reaction was stirred for one hour and concentrated. The reaction was then azeotroped with three volumes of hexane to remove excess t-butanol. Fresh hexane was added the solution was let to stand overnight to effect trituration. The red-brown solid was removed by filtration and the filtratewas washed twice with water and was concentrated. Purification by chromatography on ISCO (330 g SiO2 cartridge: stepwise hexane and then DCM) affords the title compound as a pale yellow oil (24 g, 99%). 1H-NMR (400 MHz, CDCl3) 7.29 (d, J=8.0 Hz, 1H), 7.15 (t, J=8.0 Hz, 1H), 6.76 (d, J=8.0 Hz, 1H), 5.49 (s, 1H), 4.98 (s, 1H), 3.85 (s, 3H), 2.77 (t, J=6.4 Hz, 2H), 2.53-2.50 (m, 2H), 1.93-1.87 (m, 2H).

Provenance & Evidence