Scheme 2. Synthesis of target analog 1. Reagents and conditions: (a) pTsCl (1.5 equiv.), py, 0 °C, 12 h; (b) 6 (4 equiv.), Et2O/THF (1 : 1); Li2CuCl4 (0.01 equiv.), THF, –78 °C → 23 °C, 12 h; (c) oxidation of 7a to the corresponding ketone 7b: PDC (3 equiv.), CH2Cl2, 23 °C, 5 h; (d) (Ph3PCH2Br)Br (8 equiv.), tol, ultrasound, 15 min; KOtBu in THF (7.9 equiv., 1 M), –15 °C → 0 °C, 2.5 h, then 7b in tol, –15 °C → 23 °C, 3 h; (e) tol/THF (3 : 1), –78 °C, tBuLi (2 equiv.), 1 h; B(OiPr)3 (1.5 equiv.), 1.5 h; pinacol (1.3 equiv.), –78 °C → 23 °C, 4 h; (f) 4 (1 equiv.), K3PO4 (27 equiv., aqueous sol, 2 M), THF, PdCl2(PPh3)2 (0.05 equiv.), 2 h; (g) K2CO3, MeOH, 23 °C, 14 h; (h) PhNMe2 (6.5 equiv.), tol, decaborane (B10H14, 3 equiv.), 110 °C, 1 h; (i) HF (48%, 2.5 equiv.), CH2Cl2/CH3CN (2 : 1), 23 °C, 12 h. pTsCl = p-toluenesulfonyl chloride, PDC = pyridinium dichromate, py = pyridine, tol = toluene, TBS = SitBuMe2.
