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Synthesis of new cyclazines and 4,5-diaryl-1 H -pyrrol-3(2 H)-one units in discoipyrroles from indolizinone-DMAD cycloadducts
Published in Royal Society of Chemistry
PMID: 31556900
Volume: 17
Issue: 39
Pages: 8832 - 8848
The reaction of indolizinones with dimethyl acetylenedicarboxylate gave direct access to 3′,8a-dihydrocyclopenta[hi]indolizin-8a-ol and 1H-pyrrol-3(2H)-one in good yields. The former skeleton is a precursor to cyclazines with nitrogen on the periphery, a hitherto un-accessed 10-π system. Their formation involves initial [4 + 2] or [8 + 2] modes of cycloadditions; the retro-Diels Alder reaction of the [4 + 2] cycloadduct leads to 1H-pyrrol-3(2H)-one, whereas [8 + 2] addition followed by π-reorganization leads to the azatricyle. Analysis of substituent effects on product distribution showed that electron donating groups on the C3-aryl ring promote the formation of the azatricycle preponderantly. Treatment of one of these azatricycles (3c) with HBF4 led to the formation of the corresponding 10e-aromatic species which was detected by NMR spectroscopy. In addition, formation of the 1H-pyrrol-3(2H)-one skeleton through the normal retro-Diels Alder pathway was employed in the total synthesis of Discoipyrrole C, which is a new lead against lung cancer. © 2019 The Royal Society of Chemistry.
About the journal
JournalData powered by TypesetOrganic and Biomolecular Chemistry
PublisherData powered by TypesetRoyal Society of Chemistry
Open AccessNo
Concepts (11)
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    Electron-donating group
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    Product distributions
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    Substituent effect
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    Total synthesis
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