3',4'-Dimethoxycinnamic acid → 3,4-Dimethoxycinnamoylchloride

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Reaction Steps

To a mixture of 3,4-dimethoxycinnamic acid (540 mg), DMF (2 drops) and tetrahydrofuran (10 ml) was added oxalyl chloride (0.27 ml) dropwise. The mixture was stirred at room temperature for 40 minutes, at the end of which time the solvent was distilled off to give 3,4-dimethoxycinnamoyl chloride. The chloride was dissolved in dichloromethane (10 ml) followed by addition of 3-amino-4-(2-methylphenyl)-7,8-dihydrocyclopenta[g][1]benzopyran-2(6H)-one (582 mg) and N,N-dimethylaniline (0.25 ml). The mixture was then stirred at room temperature for 20 hours, after which it was washed with water, dried (MgSO<) and distilled to remove the solvent. The residue was chromatographed on silica gel and eluted with benzeneacetone (9:1) to give 3-(3,4-dimethoxycinnamoylamino)-4-(2-methylphenyl)-7,8-dihydrocyclopenta[g][1]benzopyran-2(6H)-one as oil. The oil was crystallized from ethanol-isopropyl ether (648 mg, 67.4%). Recrystallization from acetone gave colorless needles, m.p. 159°-160° C.

Provenance & Evidence