A tandem radical approach to the ABCE-rings of the Aspidosperma and Strychnos alkaloids

Abstract

published as an Advance Article on the web Reaction of indole 19 via the derived aryl radical gives the tetracycle 20 in 43% yield. This compound contains the ABCE-rings of both Aspidosperma and Strychnos alkaloids.

The tandem radical route to indole alkaloids: an unusual rearrangement reaction

“…1 As part of our ongoing interest in these classes of alkaloids, 2 we are particularly concerned with a synthesis of the core tetracyclic sub-structure 1, which forms the basis of these molecules as exemplified by strychnine 2 and aspidospermidine 3 ( Figure 1). Following the successful cyclisation of the N-pentenyl precursor 4 in our previous example, 3 we decided to use the same conditions for cyclisation of the N-pentynyl precursor 6.…”

NMR and HPLC study of chiral selectors with naphthyl unit

“…According to the NMR studies, secondary amides exist exclusively in trans conformation [2] due to the formation of polymeric associates through hydrogen bonds between carbonyl groups and the N-H groups of the neighbouring molecules [11]. Tertiary amides do not form these intermolecular hydrogen bonds and the presence of two isomers (rotamers) could be noted [12,13]. During the course of our study on chiral selectors with naphthyl group, two sets of proton and carbon resonances were repeatedly observed.…”

A Review on Recent Developments in Syntheses of the Post-Secodine Indole Alkaloids. Part I: The Primary Alkaloid Types

“…A model study of the ABCD tetracyclic lactam formation through radical translocation/cyclisation cascade was reported by Jones et al 123 , Scheme 53. Although the treatment of bromide 341a with Bu 3 SnH failed to give any tetracycle 342a and debromo amide 343a was the major product (50%), an analogous reaction with Bu 3 SnD clearly demonstrated that the radical translocation had indeed taken place: The deuterio lactam 343b was again the major reaction product.…”