configuration 3 traces 1h nmr 400 mhz cdcl 3 d6 u03b4 4 87 4 75 d 1h 2 53 t 1h 2 11 s 3h 2 00 m 1h 0 95 m 1h 0 80 m 1h 0 78 s 3h 0 60 s 3h 3 u03b1 fluor 5 u03b1 pregnan 20 one 10 mmol is dissolved in dichloromethane 5 ml and ethanol 50 ml at rt and air atmosphere in a 250 ml round bottom flask 4 equiv of nh 2 oh chlorhydrate and 4 equiv of sodium acetate are dissolved in 5 ml h 2 o and then added to the steroid solution 20 ml of ethanol are added and the mixture put on reflux overnight the mixture is then cooled and the solvent removed under reduced pressure the white residue is then treated with 50 ml h 2 o and 50 ml dichloromethane the aqueous phase extracted with 3 u00d7 30 ml dichloromethane the collected organic phases are then dried over mgso 4 filtrated and the solvent removed under reduced pressure the final residue is purified by silica flash column chromatography dichloromethane diethyl ether 4 1 quantitative yield 1 h nmr 400 mhz cdcl 3 d6 u03b4 4 90 4 78 d 1h 2 26 t 1h 2 10 m 1h 1 90 s 3h 0 98 m 1h 0 82 s 3h 0 65 s 3h was obtained by using the same synthetic protocol as example 7 for uc2030 starting from the corresponding 3 u03b2 fluor 5 u03b1 pregnan 20 one isomer 525 mg progesterone are dissolved in 10 ml dry toluene at rt 3 4 ml 2 equiv of a 1 0 m solution of sodium t buthylate in dry toluene is added dropwise to the progesterone solution under stirring and n 2 atmosphere.