Fig. 5

The completion of the synthesis of cyrneine A. Reagents and conditions: (a) Liq. NH₃, tBuOH (1.0 equiv), K (2.5 equiv), Et₂O, −78 °C, 10 min; then LiBr (2.5 equiv), MeI (5.0 equiv), and THF were charged in situ, −78 °C, 1 h, then warmed to rt over a period of 1 h (72%); (b) 25 (5.0 equiv), NaOAc (5.0 equiv), EtOH, 35 °C, 3 h; (c) KOtAm (5.0 equiv), degassed xylene, 140 °C, 1.8 h (36% for 26; 18% for 27); (d) TBSCl (1.2 equiv), imidazole (1.2 equiv), DMF, rt, overnight (93%); (e) 5% aq. HCl, THF, 15 to 20 ^oC, 40 min (89%); (f) LiHMDS (1 M in THF, 3.5 equiv), CNCO₂Me (3.0 equiv), THF, −78 °C, 1 h; (g) ZnEt₂ (1.0 M in hexane, 6.0 equiv), CH₂I₂ (6.0 equiv), CH₂Cl₂, rt, 2 h; I₂ (7.0 equiv), rt; then saturated aq. Na₂S₂O₃ (excess), rt; then DBU (20.0 equiv), rt, 10 min (73% for 2 steps); (h) TMSOTf (5.0 equiv), CH₂Cl₂, -25 ^oC, 15 min; (i) LiAlH₄ (6.0 equiv), Et₂O, 10 min at −78 °C, then warmed to rt; (j) MnO₂ (50 equiv), CH₂Cl₂, rt, overnight (58% in 3 steps); tAm = tert-amyl; DBU = 1,8-diazabicyclo[5.4.0]undec-7-ene; TMSOTf = trimethylsilyl trifluoromethanesulfonate