2,3-Dichloro-5,6-dicyano-1,4-benzoquinone → HCID 14748413, compound

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Reaction Steps

The crude dihydropyridine intermediate is dissolved in benzene (100 ml) and heated to 65°. A solution of 2,3-dichloro 5,6-dicyanobenzoquinone (5.0 q) in warm benzene (50 ml) is added dropwise with stirring. The reaction mixture is stirred at 65° for one hour and then cooled to room temperature. The mixture is washed with 10% aqueous sodium bicarbonate (two portions of 100 ml each) and water (100 ml), then extracted with 2N hydrochloric acid (two portions of 150 ml each). The combined acid extracts are made alkaline with dilute aqueous sodium hydroxide and extracted with diethyl ether. After drying and concentration, the title compound is obtained as an oil (0.95 g) that can be further purified by chromatography on silica gel (using 4:1 by volume hexane-ethyl acetate as eluent). Structure assignment is confirmed by nmr spectroscopy. nmr (CDCl3): δ (ppm) 4.16 (s, 2H); 7.14-7.40 (m, 7H); 8.46 (d, 1H).

Provenance & Evidence