Phenol → Estra-4,9,16-trien-3-one

Estra-5(10),16-dien-3-one (3) (0.38 g, 1.5 mmole), in pyridine (5.0 mL, 62 mmol) was cooled in an ice-salt bath to -13° C. and pyridinium bromide perbromide (1.58 g, 4.94 mmole) was added in small portions so that T<-4° C. After swirling 1 min. phenol (0.25 g, 2.7 mmole) was added and reaction continued 24 h at room temperature. Ethyl acetate (50 ml) was added and the reaction mixture was washed with 25 ml of 1N HCI, two 25 ml portions of saturated copper sulfate, 25 ml of 5% sodium hydroxide, and 25 ml of brine. After drying over magnesium sulfate, filtration, and concentration under reduced pressure the residue was taken up in 10 mL of abs. ethanol, granular zinc (0.33 g, 5.0 mg-atom) was added, and the mixture was refluxed 1/2 h. The supernatant was removed, the residue was washed with 10 mL of abs. ethanol, and the combined supernatants were concentrated under reduced pressure. The resulting resin was flash chromatographed on silica gel using 15% ethyl acetate/hexane as eluent. Appropriate fractions were pooled, concentrated, and then recrystallized from hexane to give solid product (117.5 mg, 0.4619 mmol, 31%), m.p. 87-92° C.