Scheme 2.

Synthesis of 14-Deoxydebenzoyldunnianin^a

^aReagents and conditions: (a) Et₃OPF₆ (3.0 equiv), proton-sponge (3.0 equiv), DCM, 50 °C, 12 h; (b) TBAF (3.0 equiv), AcOH (3.0 equiv), THF, 12 h, 50% (two steps); (c) VO(acac)₂ (10 mol%), TBHP (ca. 5 M in decane, 2.5 equiv), PhH, 45 °C, 15 h, 99%; (d) KOH (10 wt% in H₂O, 10.0 equiv), EtOH, 3 h; (e) Me₄NBH(OAc)₃ (3.0 equiv), MeCN/THF/AcOH (4:1:1), –40 °C, 12 h, 38% (two steps); (f) Me₄NBH(OAc)₃, MeCN/AcOH (3:1), –40 °C, 12 h; (g) NaH (60 wt% in mineral oil, 3.0 equiv), THF, 1 h, 95% (two steps from 52) or 71% (two steps from 51); (h) LDA (3.0 equiv), THF, –78 °C, 1 h, 71%; (i) OsO₄ (1.2 equiv), pyridine, 12 h, then add NaHSO₃ (10.0 equiv), MeOH/H₂O (3:1), 60 °C, 4 h, 63%; (j) OsO₄ (1.2 equiv), pyridine, 12 h, then add NaHSO₃ (10.0 equiv), MeOH/H₂O (3:1), 60 °C, 4 h, 94%; (k) TPAP (10 mol%), NMO (2.1 equiv), DCM/MeCN (9:1), 18 h; (l) LiAlH₄ (2.0 M in THF, 3.1 equiv), THF, –78 °C, 2 h, 75% (two steps). Proton-sponge = 1,8-bis(dimethylamino)naphthalene, TBAF = tetra-n-butylammonium fluoride, TBHP = tert-butyl hydroperoxide, LDA = lithium diisopropylamide, TPAP = tetrapropylammonium perruthenate, NMO = N-methylmorpholine N-oxide.