Scheme 2a.
a Reagents and conditions: (a) i. SOCl2, reflux, 2 h; ii. PhNH2, K2CO3, THF, room temp., 24 h; (b) i. n-BuLi, THF, −78 °C (0.5 h) to 0 °C (0.5 h); ii. DMF, −78 °C (1 h) to 0 °C (1 h); (c) NaBH4, MeOH, room temp., 5 h; (d) 15% HCl, 60 °C, 2 d; (e) NBS, AIBN, CCl4, CH2Cl2, reflux, 2 d; (f) H2O, reflux, 2 h; (g) i. NaOMe, MeOH, EtOAc, reflux, 15 h, then HCl; ii. Ac2O, reflux, 6 h.