Fig. 5: Total synthesis of (-)-cepharatines A (5) and C (6). | Nature Communications

Fig. 5: Total synthesis of (-)-cepharatines A (5) and C (6).

From: Unified divergent strategy towards the total synthesis of the three sub-classes of hasubanan alkaloids

Fig. 5

Reagents and conditions: (a) isopropenylboronic acid pinacol ester (45, 10.0 equiv), Grubbs second-generation catalyst (0.1 equiv), DCM, 50 °C, then NaBO3.4H2O (5.0 equiv), THF/H2O = 1/1, rt, 62%; (b) 0.5 M NaOMe in MeOH, reflux, 70%; (c) LHMDS (2.0 equiv), MoOPH (3.0 equiv), THF, −78 °C to −20 °C, 74%; (d) DDQ (10.0 equiv), DCE, 50 °C, 68%; (e) DMP (1.3 equiv), DCM, 0 °C to rt, then TFA, 78%; (f) H2SO4 (1 M in MeOH)/CH(OMe)3/MeOH = 0.1/1/1, 65 °C, 95%.

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