Scheme 8. Synthesis of fluorohexestrol 2. Reaction conditions: (a) 1-bromopropane (3.0 equiv.), 2,4,6-triisopropylbenzoic acid (1.0 equiv.), NBu₄HSO₄ (0.08 equiv.), NaOH (3.0 equiv.), CHCl₃/H₂O (1 : 1), 84% yield; (b) neopentylglycol (1.0 equiv.), Et₂O, r.t., 16 h; MgSO₄ (3.0 equiv.), r.t., 2 h, 95% yield; (c) 37 (1.8 equiv.), (–)-sparteine (1.7 equiv.), sBuLi (1.7 equiv.), Et₂O, –78 °C, 5 h; 38 (1 equiv.), –78 °C, 1 h; reflux, 15 h, 46% yield; (d) CbCl (1.2 equiv.), Et₃N (1.3 equiv.), toluene, μW, 150 °C, 2 h, 98% yield; (e) TMEDA (1.3 equiv.), sBuLi (1.3 equiv.), Et₂O, –78 °C, 1 h; (R)-40 (1.5 equiv.), –78 °C, 3 h; r.t., 14 h, 70% yield; (f) TBAF·3H₂O (3.0 equiv.), toluene, reflux, 3 h, 81% yield; (g) BBr₃ (3.0 equiv.), CH₂Cl₂, –20 °C, 30 min; 4 °C, 15 h, 72% yield. TIB = 2,4,6-triisopropylbenzoyl, sBuLi = sec-butyllithium, TMEDA = N,N,N′,N′-tetramethylethylenediamine, TBAF·3H₂O = tetrabutylammonium fluoride trihydrate.