Synthesis of 12 by Scheerer et al.50 Reagents and conditions: (a) propyne, n-BuLi, Et2O, −78 °C; (b) (R)-β-Methyl-CBS catalyst, BH3•Me2S, −30 °C; (c):(1) KH, H2N(CH2)3NH2, 0 °C; (2) Me3Al, Cp-2ZrCl2, I2, −45 °C; (3) TESCl, imidazole; (d) Ni-(R)-BINAP(OTf)2, 2,6-lutidine, BF3•OEt2, HC(OMe)3; (e) HO2CCH2CO2Et, i-PrMgCl, 65 °C ; (f) LiHMDS ; ClPO(OEt)2 ; (g) Fe(acac)3, MeMgCl, −20 °C; (h):(1) DIBAL-H, −78 °C; (2) MnO2; (3) Sn(OTf)2, N-ethylpiperidine, chiral auxiliary, −78 °C; (i): (1) TBSOTf, 2,6-lutidine; (2) K2CO3, CH3OH; (3) OsO4, NMO, NaIO4; (4) Zn(OTf)2, (−)-N-Methyl-ephedrine, Et3N, 4-phenyl-1-butyne; (j):(1) BOMCl, NaHMDS, −78 °C; (2) Lindlar catalyst, H2; (3) K2OsO4, NMO, citric acid, 50 °C, Pb(OAc)4, K2CO3; (k) 27, n-BuLi, MgBr•OEt2, CH2Cl2, −78 to 0 °C; (l): (1) TBSOTf, 2,6-lutidine; (2) PPTS, CH3OH; (3) LiOH, i-PrOH, H2O; (m):(1) MNBA, DMAP, [0.0015 M]; (2) TBAF; (3) Dess-Martin periodinane; (n) TBAF, −78 to 5 °C; (o): (1) NaH, Comins reagent; (2) Pd(OAc)2, dppf, Et3SiH; (3) L-selectride, t-BuOH, −78 to −55 °C; (p) LiBF4, acetonitrile/H2O; (q) NaClO2, TMSCHN2; (r) K2CO3, CH3OH; (s) Ac2O, pyridine, DMAP.