Scheme 1.
Synthesis of BCHP (5)
Reagents and Conditions a) n-BuMgCl, CuBr•DMS (20 mol%), −40 °C; then allylBr, Pd(PPh3)4 (10 mol%), 85%; b) OsO4 (3 mol%), NaIO4, EtOAc/H2O, 73%; c) NH4OAc, MeOH, reflux 98%; d) HCl, 14, then; NaOMe, MeOH, 80%.
Synthesis of BCHP (5)
Reagents and Conditions a) n-BuMgCl, CuBr•DMS (20 mol%), −40 °C; then allylBr, Pd(PPh3)4 (10 mol%), 85%; b) OsO4 (3 mol%), NaIO4, EtOAc/H2O, 73%; c) NH4OAc, MeOH, reflux 98%; d) HCl, 14, then; NaOMe, MeOH, 80%.