A solution of 4,4-diphenyl-2-formyl-2-cyclohexen-1-one (29 g) and nitromethane (5.7 cc) in a mixture of tetrahydrofuran (250 cc) and tert-butanol (500 cc) is treated with a 35% strength solution (6.93 cc) of benzyltrimethylammonium hydroxide in methanol and stirred at 20° C. for 18 hours. The reaction mixture is diluted with ethyl acetate (500 cc) and water (2000 cc) and acidified to pH 2 with hydrochloric acid. The aqueous phase is extracted with ethyl acetate (200 cc) and the combined organic phases are washed with water (500 cc) and saturated sodium chloride solution (250 cc), then dried over magnesium sulphate and concentrated to dryness under reduced pressure (2.7 kPa). The crystallized residue is stirred in a mixture (100 cc) of cyclohexane and ethyl acetate (80:20 by volume) and the crystals are drained and washed with the same mixture (20 cc) and with isopropyl ether (2×50 cc). 4,4-Diphenyl-2-formyl-3-(nitromethyl)cyclohexanone (24.7 g) is obtained in the form of cream-colored crystals, m.p. 188° C.
