The Alkaloids of Tabernanthe iboga. Part VIII¹

Abstract

Vol. 81 priate acid chloride. The mixture was cooled, solvents evaporated almost to dryness in vacuo; water added and the gum triturated and washed with excess water yielding the desired compound in the form of its hydrochloride. Conversion of the crude salt to the free base was accomplished by slurrying in methanol solution for 10 minutes with an equal weight of silver carbonate. After filtration from silver salts and evaporation of the methanol the ester was crystallized from one of the solvents listed in B.

Organocatalytic Enantioselective Synthesis of Chiral Spiro‐indoline‐pyrazolones through a formal [4+1] Annulation Reaction of 4‐Bromopyrazolones and aza‐ortho‐Quinone Methides

“…The diastereomeric ratio (dr) was determined via 1 H-NMR analysis. NMR spectra were carried out in a Bruker Avance III HD spectrometer at 300 MHz for 1 H and at 75 MHz for 13 C, in a Bruker AV400 spectrometer at 400 MHz for 1 H and at 100 MHz for 13 C or in a Bruker Neo500 spectrometer at 500 MHz for 1 H and at 126 MHz for 13 C using residual non-deuterated solvent as internal standard (CHCl 3 : δ 7.26 for 1 H and 77.0 ppm for 13 C). Chemical shifts are given in ppm.…”

“…[10][11][12] Among the spirocyclic compounds, spiroindolines represent an interesting scaffold present in several compounds with biological activities (Figure 1A). [13][14][15][16] One straightforward way to synthesize chiral C2-spiroindolines is using a formal [4 + 1] cycloaddition through an aza-ortho-quinone methide intermediate. [17,18] However, only one example has been described in the literature using chiral sulfur ylides (Scheme 1A).…”

Chemical Diversity and Bioactivities of Monoterpene Indole Alkaloids (MIAs) from Six Apocynaceae Genera

“…Another study on the twigs and leaves of E. officinalis led to the reporting of three MIAs, ervaoffines E–G ( 345 – 347 ) [ 179 ], and six compounds 306 , 342 , lirofoline A ( 348 ), lirofoline B ( 349 ) [ 172 ], 6-oxo-ibogaine ( 350 ) [ 180 ], and 8-oxo-ibogaine lactam ( 351 ) [ 179 , 180 , 181 ]. Compound 347 showed a significant neuroprotective effect towards damage induced by oxygen-glucose deprivation (OGD) of the cortical neurons cultured of ischemic stroke in vitro, with an IC 50 = 100 μM, Neuroserpin was used as a reference drug, with an IC 50 = 20 ng/mL [ 179 ].…”

“…Seven compounds, 3-oxo-7R-coronaridine hydroxyindolenine (333), 3S-cyano-7Scoronaridine hydroxyindolenine (334), 3R-hydroxy-7S-coronaridine hydroxyindolenine (335), 3S-(24S-hydroxyethyl)-coronaridine (336), 3S-(24R-hydroxyethyl)-coronaridine (337), 5-oxo-6S-hydroxycoronaridine (338) and 5-oxo-6S-methoxy-coronaridine (339) [175], along with six others, 306, 7S-coronaridine hydroxyindolenine (340) [176], 3-oxo-7S-coronaridine hydroxylindolenine (341) [177], 5-oxocoronaridine (342) [177], 3-oxocoronaridine (343) [178] and pseudoindoxyl coronaridine (344) [177], (Figure 27) from identified from twigs and leaves of E. hainanensis [175]. Another study on the twigs and leaves of E. officinalis led to the reporting of three MIAs, ervaoffines E-G (345-347) [179], and six compounds 306, 342, lirofoline A (348), lirofoline B (349) [172], 6-oxo-ibogaine (350) [180], and 8-oxo-ibogaine lactam (351) [179][180][181]. Compound 347 showed a significant neuroprotective effect towards damage induced by oxygen-glucose deprivation (OGD) of the cortical neurons cultured of ischemic stroke in vitro, with an IC 50 = 100 µM, Neuroserpin was used as a reference drug, with an IC 50 = 20 ng/mL [179].…”

New Strategies for the Synthesis of Monoterpene Indole Alkaloids

“…However, this structural pattern was accessed by partial synthesis a long time before in the Iboga alkaloid series [30], and in the yohimbine family [31]. However, this structural pattern was accessed by partial synthesis a long time before in the Iboga alkaloid series [30], and in the yohimbine family [31].…”