[F:1][C:2]1[CH:3]=[CH:4][C:5]2[O:10][CH2:9][CH2:8][C:7]([C:16]#[N:17])(O[Si](C)(C)C)[C:6]=2[CH:18]=1.P(Cl)(Cl)(Cl)=O.Cl>N1C=CC=CC=1.O>[F:1][C:2]1[CH:3]=[CH:4][C:5]2[O:10][CH2:9][CH:8]=[C:7]([C:16]#[N:17])[C:6]=2[CH:18]=1To a solution of 32 g (0.12 mole) of the crude 6-fluoro-2,3-dihydro-4-cyano-4-[(trimethylsilyl)oxy]-4H-benzopyran in 170 ml of dry pyridine was added 60 ml (0.6 mole) of phosphorous oxychloride. The reaction was heated to reflux for 5 hours then cooled to room temperature. The resulting solution was added dropwise to a solution of 300 cc of concentrated HCl in 1 L of water. This aqueous layer was extracted with EtOAc and the EtOAc layer was dried over Na2SO4, filtered and evaporated to give 16.1 g of product m.p. 114°-115° C.
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