19-Nor-17β-hydroxy-17α-trifluoromethyl-Δ⁴-estren-3-one 6 and its analogs 7 and 8 have been synthesized in total yields of 82%, 54% and 27%, respectively, using Me₃SiCF₃ as a trifluoromethylating agent. The three compounds showed high affinity for rat uterus PRc. Trifluoromethyl-substituted compounds have been examined for their potential as biologically active drugs and agrochemicals. The trifluoromethyl group is one of the most lipophilic substituents and can increase the solubility of drugs in lipids, thus enhancing their penetrating ability. Since its size is close to that of the methyl group, it does not seriously modify the steric bulk of the steroid, thus ensuring a good fit to the target receptor. The high electron-attracting properties could alter the reactivity of neighbouring groups, causing a possible modification of biological activity of the molecule. So we aim to synthesize some trifluoromethyl-substituted steroids to find new compounds for contraceptive drugs. However, the introduction of a trifluoromethyl group is more difficult than that of a single fluorine atom, thus it is not surprising that only a limited number of steroids bearing this group appear in the medicinal chemical literature. The direct introduction of a trifluoromethyl group using Me₃SiCF₃ (TMSCF₃) reagent has been reported. But this method is not very useful for hindered carbonyl compounds. We have recently reported an improved synthetic method for efficient trifluoromethylation of hindered steroid compounds with TMSCF₃ reagent promoted by Me₄NF followed by 40% aq.HF hydrolysis and obtained some trifluoromethyl-substituted steroids in almost quantitative yield. When the useful contraceptive drug 11β-(p-N,N-dimethylaminophenyl)-17α-propynylestra-4,9-diene-17β-ol-3-one (RU486) (I) was modified by a trifluoromethyl group at the 17 position, the analog 2 exhibited increased bioactivity in biotests, as we have envisaged. Norethisteron (17α-ethynyl-19-nor-testosterone) (3) and some of its derivatives are potent progestogens (such as 4 and 5) widely used for oral contraception. Recently, the influence of 17 position substituents of these derivatives on the binding affinity to progesterone and androgen receptors has been investigated and some factors were suggested: a) steric changes over the whole molecule may influence the binding affinity; b) the alcohol group at C-17 requires particular consideration and it might be expected that the electron density at O-17, which may be changed by the chemical modifications, is responsible for the binding affinities. In this report, we described the synthesis of 19-nor-17β-hydroxy-17α-trifluoromethyl-Δ⁴-, Δ⁴,9- and Δ⁴,9,11-estren-, estradien- and estratrien-3-one (6, 7 and 8) (scheme 1) as potent bioactive compounds compared with I and 2.