A Unified Synthetic Strategy for the Indolopyridine Alkaloid Group

Abstract

Thermal or acetyl chloride induced cyclization of bromoenamide 10 affords the pentacyclic derivative 12 with high yield and regioselectivity. From this common synthetic intermediate, palladium‐catalyzed reactions allow the total synthesis of indolopyridine alkaloids 1–6.

Recent developments in the chemistry of dihydropyridines

“…13 An intramolecular enamide addition taking place on 3,5-disubstituted N-acetylpyridinium salt 21 was used to regioselectively build the common pentacyclic intermediate for the synthesis of six indolopyridine alkaloids. 21 In this case, oxidation and hydrolysis of the initially formed dihydropyridine afforded the desired compound 22 (Scheme 6).…”

Synthesis, kinase inhibitory potencies and in vitro antiproliferative activity of isoindigo and 7′-azaisoindigo derivatives substituted by Sonogashira cross-coupling

“…None of the tested compounds have shown any cytotoxicity toward the cell lines tested when the final concentration of the tested compounds used was 10 −6 M ( Table 1). Only five compounds (two isoindigo derivatives (3,8) and three 7′-azaisoindigo (10, 13, 15) analogues) have shown modest antiproliferative activities when tested at 10 −5 M. In the isoindigo series, the most active compound was compound 3, bearing a sugar moiety and an iodine atom at the 5′-position, which inhibited the cell proliferation for both cell lines nearby 50%. Moreover, compound 8, bearing a sugar moiety and a hydroxybut-3-ynyl side chains in the 5′-position, suppressed the cell proliferation of K562 cells by 51%.…”

“…Unfortunately, no coupling product was obtained (Scheme 2). Then, we decided to activate the 5-position of the 7-aza-5-bromoindolin-2-one 9 by preparing the iodinated analogue either in the presence of KI and CuI in dimethylformamide as described for 3,5-dibromopyridine [7] or with BuLi and iodine in THF as described by Lavilla for 5-bromonicotinic acid [8]. In both conditions, no halogen exchange was observed.…”