6393-66-4Relevant articles and documents
Bioinspired Divergent Oxidative Cyclizations of Geissoschizine: Total Synthesis of (–)-17-nor-Excelsinidine, (+)-16-epi-Pleiocarpamine, (+)-16-Hydroxymethyl-Pleiocarpamine and (+)-Taberdivarine H
Jarret, Maxime,Tap, Aurélien,Turpin, Victor,Denizot, Natacha,Kouklovsky, Cyrille,Poupon, Erwan,Evanno, Laurent,Vincent, Guillaume
, p. 6340 - 6351 (2020/09/07)
We report a full account of our efforts towards bioinspired oxidative cyclizations of geissochizine and analogs to mimic the biosynthesis of the mavacuran, akuammilan, and excelsinidine groups of monoterpene indole alkaloids. The construction of the A,B,C,D ring system of geissoschizine was first achieved by merging two known syntheses of this alkaloid. Modified Ma's oxidative conditions (KHMDS/I2) applied directly to geissoschizine induced formation of the N4–C16 bond encountered in the excelsinidines core. Identical conditions applied to C16-dimethylmalonate-containing N4-quaternized substrates ended in the formation of the mavacurans core (N1–C16 bond). With this unified oxidative cyclization strategy: (–)-17-nor-excelsinidine, (+)-16-epi-pleiocarpamine, (+)-16-hydroxymethyl-pleiocarpamine, 16-formyl-pleiocarpamine and (+)-taberdivarine H were synthetized. We also report a shortened total synthesis of 16-epi-pleiocarpamine compared to our preliminary communication from a C16-monoester analog. Alternatively, 17-nor-excelsinidine was synthesized via an intramolecular nucleophilic substitution of a 7-membered ring α-chlorolactam prepared from 16-desformyl-geissoschizine.
Total Syntheses of Pleiocarpamine, Normavacurine, and C-Mavacurine
Sato, Keigo,Kogure, Noriyuki,Kitajima, Mariko,Takayama, Hiromitsu
supporting information, (2019/05/08)
The total syntheses of C-mavacurine-type indole alkaloids, (±)-pleiocarpamine, (±)-normavacurine, and (±)-C-mavacurine, were accomplished. The key step in the syntheses was the cyclization between the metal carbenoid at C16 and the N1 position in a Corynanthe-type compound that was equipped with a diazo function. For this cyclization, the N4 modification of the substrate using an amine-borane complex was indispensable to fix the molecular conformation.
THE TOTAL SYNTHESIS OF (+-)-C-MAVACURINE
Calverley, M. J.,Banks, B. J.,Harley-Mason, J.
, p. 1635 - 1638 (2007/10/02)
The processes of reductive opening and oxidative reclosing of the 3,4-bond have been applied to effect overall epimerisation at C-3 in the transformation of synthetic epi-geissoschizine analogues into mavacurine-type alkaloids.
