Acetic Anhydride → trans-3-acetoxy-4-(2-cyanoimino-3-methylimidazolidin-1-yl)-3,4-dihydro-2,2-dimethyl-2H-1-benzopyran-6-carbonitrile

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Reaction Steps

To a solution of trans-4-(2-cyanoimino-3-methylimidazolidin-1-yl)-3,4-dihydro-3-hydroxy-2,2-dimethyl-2H-1-benzopyran-6-carbonitrile (0.95 g) in dry pyridine (9.5 ml) was added acetic anhydride (0.68 ml) at ambient temperature. The reaction mixture was stirred for 21 hours and 20 minutes at ambient temperature and then diluted with ethyl acetate (90 ml). The resultant solution was washed successively with 10% hydrochloric acid (50 ml, 30 ml), water (50 ml), saturated aqueous sodium bicarbonate (50 ml), dried over magnesium sulfate, and evaporated in vacuo. The residue was triturated with diisopropyl ether, and recrystallized from ethanol to give trans-3-acetoxy-4-(2-cyanoimino-3-methylimidazolidin-1-yl)-3,4-dihydro-2,2-dimethyl-2H-1-benzopyran-6-carbonitrile (0.57 g).

Provenance & Evidence