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Reagents and conditions: a) Lauroyl peroxide, cyclohexane/ClCH2CH2Cl (7.2:1), reflux, 2 h, 92%; b) TfOH, 5 Å molecular sieves, CH2Cl2/Et2O (2:1), r.t., 3 h, 91% (α/β 4:1, isolated 9α: 67%, 9β: 16%); c) Pd-C (10%), H2 (1 bar), MeOH, r.t., 4 h; then 0.1 M NaOMe, MeOH, r.t., 17 h; then 0.1 M aq. NaOH, 0 °C → r.t., 4 h, 94%.
