Total syntheses of (±)-teleocidin B-3 and B-4 - …
C−C Bond Formation via C−H Bond Activation: Synthesis of the Core of Teleocidin B4
Synthesis of teleocidins A, B and their congeners
T1 - A model study for the synthesis of the tumor promoting agents lyngbyatoxin a and teleocidin b-further aspects of a new isoxazoline-based indole synthesis.
Tumor-promoter teleocidins and their active congeners (indolactams) are known to exist in an equilibrium between at least two conformational states in solution, the twist and sofa form, due to − isomerization of the amide bond and the steric effects of substituents on the nine-membered lactam ring. Benzolactam-Vs, in which the indole ring of indolactams is replaced with a benzene ring, were designed and synthesized in an attempt to reproduce the active conformation of teleocidins. Among these benzolactams, eight-membered lactams (benzolactam-V8) can only exist in the twist form, and 9- and 10-membered lactams (benzolactam-V9 and -V10) exist exclusively in the sofa form in solution. The stronger biological activity of benzolactam-V-8-310 than that of indolactam-V (IL-V) and the inactivity of benzolactam-V-9-310 for differentiation inducing activity of HL-60 clearly indicated that the twist form is close to the active conformation of teleocidins.
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In the preparation of a library of the tumor-promoting teleocidin, the synthesis of the N13-des(methyl)indolactam V core structure has been carried out by means of TBTU: HOBt in -methylpyrrolidone (NMP) in solution-phase and in solid-phase (). In the synthesis of seco forms of the peptide metabolite diazonamide A, a potent tumor-growth inhibitor, the amide bond of the ring and the valine appendage have been incorporated by means of the combination TBTU:DIEA.
A critique of “C-C Bond Formation via C-H Bond Activation: Synthesis of the Core of Teleocidin B4,” Brenton DeBoef and Scott R. Gilbertson, 16, 249, (2003).
Synthesis of a tetramethyl analog of teleocidin - …
The core of teleocidin B4, a complex fragment of a natural product containing two quaternary stereocenters and a penta-substituted benzene ring, was synthesized in four C−C bond-forming steps starting from -butyl derivative 1. The first step involved alkenylation of the -butyl group with a vinyl boronic acid, followed by the successful annulation of the cyclohexane ring to the benzene nucleus via an intramolecular Friedel−Crafts reaction. The third step required a diastereoselective oxidative carbonylation of the geminal dimethyl group, followed at last by indole assembly via the alkenylation of the phenol nucleus, to afford the teleocidin B4 core. Noteworthy is the fact that steps 1 and 3 critically depended on the directing role of the aniline nitrogen (directed C−H bond functionalization).
C−C Bond Formation via C−H Bond Activation: Synthesis …
teleocidin (Concept Id: C0076068)
| A simplified tetramethyl analogue 3 of Teleocidin B-4 (1) has been synthesized from dinitrotoluene 6 via indole 4
The synthesis of analogues of active substances ..
Synthestic approaches to the teleocidin-related tumour promoters: a total synthesis of (±)-indolactam V
BERBERINE: Uses, Side Effects, Interactions and …
The core of teleocidin B4, ..
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