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. Author manuscript; available in PMC: 2021 Apr 5.
Published in final edited form as: J Am Chem Soc. 2021 Mar 17;143(12):4732–4740. doi: 10.1021/jacs.1c00457

Scheme 2. Synthesis of C-ring cleaved lycodine alkaloids from protected β-obscurine.a.

Scheme 2.

aReagents and conditions: (a) RuO2• H2O, NaIO4, H2O, 21 °C, then 24, tBuOH, 60 °C (86%); (b) aq. 1 M LiOH, THF, 30 °C; (c) MeI, Ag2CO3, CHCl3, 75 °C (86%, 2 steps) (d) aq. 1 M LiOH, THF, 65 °C (97%); (e) PdBr2, DPE-Phos, Piv2O, Et3N, DMPU, 130 °C (65%) (f) TMSI, CHCl3, 65 °C (89%) (g) Sm, aq. 3 M HCl, 0 to 21 °C (84%) (h) Pd(dba)2, P(tBu)3, iPrCOCl, toluene, 90 °C (81%) (i) TMSI, CHCl3, 65 °C (41%).