The structure and stereochemistry of clivonine

Phytochemical and Biological Investigation of Hymenocallis littoralisSalisb.

“…The large coupling constant between HÀC(11b) and HÀC(11c) (J ¼ 9.4 Hz) in the 1 H-NMR spectrum of 2 implied trans-diaxial substitution, and the negligible coupling between HÀC(11b) and HÀC(5a) indicated an axial/equatorial disposition and, consequently, cis-fused B/C rings. Moreover, the small coupling constant for HÀC(5a) and HÀC (5) suggested that the 5-OH group was a-configured [8] [9]. This stereostructure was in agreement with the diagnostic 1 H-NMR chemical shift of the N-methyl group at d(H) 2.04 [8].…”

Total Synthesis of the Lycorenine-Type Amaryllidaceae Alkaloid (±)-Clivonine via a Biomimetic Ring-Switch from a Lycorine-Type Progenitor

“…However, freeze-drying of this mixture, suspension of the residue in toluene and treatment with Fetizon's reagent reproducibly afforded (±)-clivonine (19) in 32% yield after chromatography from iminium salt 15 (12 steps, 6.1% overall yield from enone 6). All spectroscopic data matched that reported for the natural material 14,15,25 and its molecular structure was confirmed by a single-crystal X-ray structure determination on its hydrochloride (Scheme 3).…”

Total synthesis of the Amaryllidaceae alkaloid clivonine

“…aq. NH 4 Cl (20 mL), the aqueous phase extracted with CH 2 Cl 2 (30 mL), the combined organic phases dried over Na 2 SO 4 (7), 343 (10), 268 (6), 121 (26), 111 (18), 97 (29), 85 (27), 69 (56) To a solution of lactam (-)-19 (12 mg, 0.03 mmol) in THF (3 mL) at RT was added LiAlH 4 (4 mg, 0.11 mmol). After stirring for 2 h, the reaction mixture was quenched with brine (3 mL) and concentrated in vacuo.…”