Tributylamine → 2H-1-Benzopyran-2-one, 4-chloro-6-methoxy-

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Reaction Steps

A stirred mixture of 4-hydroxy-6-methoxycoumarin (116 g, 0.603 mole) and POCl3 (462.29 g, 3.015 mole) in toluene is treated dropwise with tri-n-butylamine (250 mL, 1.73 mole) at 25° C., heated at 100°-110° C. and monitored by HPLC analysis. When the reaction is complete, the mixture is cooled to room temperature, poured over ice, stirred mechanically for about 2 hours and filtered. The filtercake is washed with water and toluene, dissolved in methylene chloride and filtered through diatomnaceous earth. The methylene chloride filtrate is concentrated and treated with a mixture of dimethylformamide and acetonitrile to afford crystallization. The mixture is filtered to give the title product, 81.7 g, (64% yield) identified by HPLC analysis.

Provenance & Evidence