Fig. 6. Synthesis of compounds 1a–c, 2a–t and 3a–t. Reagents and conditions: A: (1a) MOMBr (4.2 equiv.), DIPEA (5.2 equiv.), DCM, room temp., 4 h, 92%; (1b) TBDMSCl (2.5 equiv.), DBU (3 equiv.), Et₂O, room temp., 16 h, 76%; (1c) (Ph)₂CCl₂ (1.05 equiv.), K₂CO₃ (2.2 equiv.), ACN, room temp., 16 h, 55%; B: i) R'NH₂ (1.1 to 3 equiv.), AcOH (1.5 equiv.), MgSO₄ (3 equiv.), MeOH, room temp., 1 h, ii) NaBH₃CN (1.5 equiv.), MeOH, room temp., 16 h, 40–70% over two steps; C: HCl in MeOH (5 to 10 equiv.), 0 °C to room temp., 15 min, 20–90%; H₂O (20 equiv.), TFA, room temp., 15 min, 40–50%.