Scheme 7. Synthesis of CJ-16,264 Analogue (±)-11a.
aReagents and conditions: (a) 62 (3.0 equiv), Grubbs II catalyst 56 (0.2 equiv), CH2Cl2, 25 °C, 24 h, 63%; (b) TBAF (1.0 equiv), AcOH (2.0 equiv), THF, 0 °C, 5 min, 82%; (c) MNBA (1.4 equiv), DMAP (3.0 equiv), CH2Cl2, 25 °C, 12 h, 84%; (d) IBX (5.0 equiv), EtOAc, 70°C, 7 h, 48%; MNBA = 2-methyl-6-nitrobenzoic anhydride, DMAP = N,N-dimethylpyridin-4-amine.