[CH:1]([C:3]([CH3:5])=[O:4])=[CH2:2].C#[N:7].P(=O)(O)(O)O.C[C:14]1[C:15](O)=[C:16](C)[C:17](C)=[C:18]([CH:20]=1)O.B(F)(F)F>C1(C)C=CC=CC=1.C(N(CC)CC)C.[N+](C)([O-])=O>[C:5]([CH:3]1[CH2:1][CH2:2][C:18]2[C:20](=[CH:14][CH:15]=[CH:16][CH:17]=2)[O:4]1)#[N:7]23.7 g (0.338 mole) of methyl vinyl ketone were added over 5 minutes to a solution of 9.7 g (0.36 mole) of liquid hydrocyanic acid and 34 g of nitromethane whilst stirring, and thereafter 0.5 g of triethylamine was added slowly, first at -20° C. and then at -25° C. The reaction mixture was then kept at -20° C. for 1.5 hours. After acidifying the mixture with 1 g of phosphoric acid, 51.4 g (0.338 mole) of trimethylhydroquinone and 180 g of toluene were added, and 23.0 g (0.338 mole) of BF3 were then passed in over 1.5 hours at -10° C. After stirring for one hour at -5° C., the mixture was brought to room temperature and stirred for 5 hours. Working up by the method described in Example 1 gave pure 2-cyanochromane in 78% yield.
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