Fig. 8: Enantiodivergent total syntheses of eburnane-type alkaloids.
From: Catalytic enantioselective nitrone cycloadditions enabling collective syntheses of indole alkaloids
Reaction conditions: (a) (Boc)2O, DMAP, Et3N, 25 °C; (b) Comins’ Reagent, LiHMDS, THF, −78 °C; (c) LiCl, Pd(PPh3)4, nBu3SnH, THF, 25 °C; (d) Allyl bromide, MeCN, 25 °C, then DABCO, reflux; (e) Grubbs II, DCM, reflux, then TFA, DCM, 0–25 °C; (f) LDA, HMPA, −78 °C, then EtI, THF, −40 °C; (g) DIBAL-H, Toluene, 0 °C; (h) MsCl, Et3N, DCM, 0–25 °C; (i) TMSCN, TBAF, MeCN, 25 °C; (j) DIBAL-H, Toluene, −78 °C; (k) PtO2, H2, EtOH, 25 °C; (l) TFA, DCM, 0–25 °C; (m) TPAP, NMO, DCM, 0–25 °C; (n) DIBAL-H, Toluene, −78 °C then HCl in MeOH, 0–25 °C; (o) PtO2, H2, MeOH, 25 °C; (p) DIBAL-H, Toluene, −78 °C then HCl in EtOH, 0–25 °C.
