Scheme 4.

(−)-Aurantioclavine (2). Reagents and conditions: (a) SEMCl, Cs₂CO₃, CH₃CN, 96%; (b) Pd(OAc)₂, SPhos, Na₂CO₃, DMF, 100 °C, vinylborane 60; (c) DDQ, CH₂Cl₂/H₂O, 82% (2 steps); (d) BocNHTs, DIAD, PPh₃, THF, 88%; (e) conc. HCl, MeOH, CH₂Cl₂, 70%; (f) PhNTf₂, Et₃N, CH₂Cl₂, 87%; (g) vinylborane 59, Pd(PPh₃)₄, Na₂CO₃, EtOH/PhMe/H₂O, 100 °C; (h) DDQ, CH₂Cl₂/H₂O, 84% (2 steps); (i) ClCO₂Me, pyridine, CHCl₃, reflux; (j) TFA, CHCl₃, reflux, 87% (2 steps); (k) tBu-PHOX 66 (45 mol%), Pd₂(dba)₃ (15 mol%), Bu₄NCl (0.30 equiv.), 0 °C, CH₂Cl₂, 72 h, 77% (95% ee); (l) 2-methyl-2-butene, Grubbs 2^nd generation catalyst., 40 °C; (m) P(OEt)₃, 170 °C, 78% (2 steps); (n) NaOH (aq), THF/MeOH, reflux; (o) Cu, quinoline, 190 °C, 68% (2 steps); (p) Na/ naphthalene, DME, −78 °C, 90%