Phosphorus oxychloride → 4H-1-Benzopyran-2-carbonitrile, 7-methyl-4-oxo-

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Reaction Steps

26.41 g (17.22 mmoles) of phosphorus oxychloride is added to 100 ml dimethylformamide at 0° C. and stirred at 0° C. for 15 minutes at room temperature for 30 minutes 7.0 g (34.45 mmoles) 2-carbamyl-7-methyl-4-oxo-4H-1-benzopyran is added and the mixture stirred at room temperature overnight, then poured into ice water and is allowed to stand for 1 hour at room temperature. The resulting precipitate is filtered off, redissolved in ethyl acetate, decolorized with carbon, filtered and the filtrate concentrated in vacuo to give 4.5 g of 2-cyano-7-methyl-4-oxo-4H1-benzopyran as a crystalline solid having an m.p. of 155°-56° C.

Provenance & Evidence