The first synthesis of the benzo[b]indolo[1,2-h][1,7]naphthyridine ring system

Baranova, Olga V.; Zhidkov, Maxim E.; Dubovitskii, S. V.

doi:10.1016/j.tetlet.2011.02.106

Cited by 8 publications

(4 citation statements)

References 13 publications

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“…There have been reported syntheses of these natural products including the silver-catalyzed cascade synthesis of their parent compound and analogs, with this approach involving the initial intermolecular reaction of two components of similar molecular complexity, however, this necessitated the prior synthesis of these two components . The B-ring homologue of fascaplysin has also been synthesized starting from 4(1 H -indol-1-yl)butanoic acid in a 2 step synthesis in a best yield of 42% …”

Section: Resultsmentioning

confidence: 99%

Rapid Cascade Synthesis of Poly-Heterocyclic Architectures from Indigo

et al. 2013

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The base-induced propargylation of the dye indigo results in the rapid and unprecedented one-pot synthesis of highly functionalized representatives of the pyrazino[1,2-a:4,3-a′]diindole, pyrido[1,2-a:3,4-b′]diindole and benzo [b]indolo [1,2-h]naphthyridine heterocyclic systems, with the last two reflecting the core skeleton of the anticancer/antiplasmodial marine natural products fascaplysin and homofascaplysins and a ring Bhomologue, respectively. The polycyclic compounds 6-8, whose structures were confirmed through singlecrystal X-ray crystallographic analysis, arise from sequential inter/intramolecular substitution-addition reactions, and in some cases, ring rearrangement reactions. Preliminary studies on controlling the reaction path selectivity, and the potential reaction mechanisms, are also described. Initial biological activity studies with these new heterocyclic derivatives indicated promising in vitro antiplasmodial activity as well as good anticancer activity. The chemistry described is new for the indigo moiety and cascade reactions from this readily available and cheap starting material should be more broadly applicable in the synthesis of additional new heterocyclic systems difficult to access by other means. Preliminary studies on controlling the reaction path selectivity, and the potential reaction mechanisms, are also described. Initial biological activity studies with these new heterocyclic derivatives indicated promising in vitro anti-plasmodial activity as well as good anti-cancer activity. The chemistry described is new for the indigo moiety and cascade reactions from this readily available and cheap starting material should be applicable more broadly in the synthesis of additional new heterocyclic systems difficult to access by other means.

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Section: Resultsmentioning

confidence: 99%

Rapid Cascade Synthesis of Poly-Heterocyclic Architectures from Indigo

et al. 2013

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“…After hydrogenation (H 2 , 5 % Pd/C, EtOAc) followed by deprotection of the tert ‐butyl ester (TFA, CH 2 Cl 2 ), carboxylic acid 19 was obtained as a substrate for cyclization. The next Friedel‐Crafts type cyclization was examined by exploiting two procedures ( method A , polyphosphoric acid; [10] and method B , P 2 O 5 [15] ). Cyclization reaction using the method A [10] employing the conditions shown in Scheme 2 gave the desired heterotricycle 7 in 25 % yield.…”

Section: Resultsmentioning

confidence: 99%

“…Cyclization reaction using the method A [10] employing the conditions shown in Scheme 2 gave the desired heterotricycle 7 in 25 % yield. Gratifyingly, the yield was improved to 72 % when the method B (P 2 O 5 , p ‐xylene, reflux) [15] at a multigram preparative scale was used. The heterotricyclic system of the initially proposed structure of pACU‐B was, thus, successfully constructed.…”

Section: Resultsmentioning

confidence: 99%

Synthetic Studies on the Initially Proposed Structure of Protoaculeine B: Discovery of Neuronally Active Heterotricyclic Amino Acids

et al. 2022

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Herein, we report our results on the synthetic studies of the originally proposed structure of protoaculeine B, isolated from a marine sponge. Starting from tryptophan, two candidates of the suitably protected heterotricyclic subunits were stereoselectively synthesized over 8 and 16 steps, respectively. Furthermore, two diastereomeric heterotricyclic amino acids, finally synthesized, were found to be neuroactive: the (9S*,11S*)-isomer with natural-type configuration was hyperactive, whereas diastereomeric (9S*,11R*)-isomer was hypoactive upon mice intracerebroventricular injection.

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“…With carboxylic acid 10 in hand, a Friedel–Crafts-type cyclization was attempted for the construction of the C-ring (Scheme ). Because O -acylphosphoric acid is known to be a suitable intermediate when an indole derivative is used as the substrate, we first used polyphosphoric acid, which gave ketone 11 in 25% yield at 90 °C; however, the yield was dramatically improved to 72% when P 2 O 5 was employed in p -xylene at reflux . The structure of 11 was confirmed using NMR spectroscopy.…”

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confidence: 99%

Studies on Aculeines: Synthetic Strategy to the Fully Protected Protoaculeine B, the N-Terminal Amino Acid of Aculeine B

et al. 2018

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A synthetic strategy for accessing protoaculeine B (1), the N-terminal amino acid of the highly modified peptide toxin aculeine, was developed via the synthesis of the fully protected natural homologue of 1 with a 12-mer poly(propanediamine). The synthesis of mono(propanediamine) analog 2, as well as core amino acid 3, was demonstrated by this strategy. New amino acid 3 induced convulsions in mice; however, compound 2 showed no such activity.

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The first synthesis of the benzo[b]indolo[1,2-h][1,7]naphthyridine ring system

Cited by 8 publications

References 13 publications

Rapid Cascade Synthesis of Poly-Heterocyclic Architectures from Indigo

Rapid Cascade Synthesis of Poly-Heterocyclic Architectures from Indigo

Synthetic Studies on the Initially Proposed Structure of Protoaculeine B: Discovery of Neuronally Active Heterotricyclic Amino Acids

Studies on Aculeines: Synthetic Strategy to the Fully Protected Protoaculeine B, the N-Terminal Amino Acid of Aculeine B

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