2,2-dimethyl-2H-1-benzopyran-6-carbonitrile → 6-Cyano-3,4-dihydro-2,2-dimethyl-2H-1-benzopyran

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Reaction Steps

A solution of 6-cyano-2,2-dimethyl-2H-1-benzopyran (5.5 g, 29.7 mmoles, prepared according to Evans et al., J. Med. Chem., 1983, 26, 1582 and J. Med. Chem. 1986, 29, 2194) in anhydrous ethanol (40 ml) was treated with palladium on carbon (0.35 g) and stirred under hydrogen gas for 2 hours. The catalyst was filtered through celite and the filter cake washed with ethyl acetate. The filtrate was concentrated under vacuum to obtain 5.71 g of a yellow oil. The crude product was dissolved in ethyl acetate (60 ml) and washed successively with 5% hydrogen chloride solution (60 ml), saturated sodium hydrogen carbonate solution (60 ml), saturated sodium chloride solution (60 ml) and dried over anhydrous magnesium sulfate. The solvent was recovered under vacuum to yield 5.14 g of the title A compound as a yellow solid (m.p. 30°-31° C.) which was used in the next step without further purification. 1H NMR (CDCl3) δ 7.37 (s, 1H), 7.34 (s, 1H), 6.80 (d, J=8.8 Hz, 1H), 2.78 (dd, 2H), 1.80 (dd, 2H), 1.35 (s, 6H). 13C NMR (CDCl3) δ 157.95, 133.82, 131.34, 122.07, 119.53, 118.24, 102.66, 75.76, 32.13. 26.81. 22.06.

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