Magnesium → 6-Fluoro-3,4-dihydro-2H-1-benzopyran-4-carbonitrile

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Reaction Steps

To a solution of 16.1 g (0.092 moles) of 6-fluoro-4-cyano-2H-benzopyran in 270 mL of absolute methanol was added 5.52 g (0.23 mole) of magnesium turnings. The resulting exothermic reaction was allowed to reflux then stirred at room temperature for 2 hours. The volatiles were evaporated and the residue dissolved in water which was acidified to pH 2.0 with concentrated HCl. The aqueous was extracted with EtOAc and the EtOAc layer was dried over Na2SO4, filtered and evaporated to give 16 g of crude product. The crude aproduct was purified by chromatography and 450 g of silica gel eluting with CH2Cl2 /ether to give 9 g of product m.p. 67°-68° C. NMR CDCl3 ppm (delta): 2.25 (dt, 2H, J=5 Hz), 4.95 (s, 1H, J=5 Hz), 4.00-4.30 (m, 2H), 6.70-7.05 (m, 3H).

Provenance & Evidence