Organocascade Synthesis of Annulated (Z)-2-Methylenepyrans: Nucleophilic Conjugate Addition of Hydroxycoumarins and Pyranone to Branched Nitro Enynes via Allene Formation/Oxa-Michael Cyclization/Alkene Isomerization Sequence

Ramani Gurubrahamam, Bing Fong Gao, Yan Ming Chen, Yu Te Chan, Ming-Kang Tsai, Kwunmin Chen

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19 Citations (Scopus)

Abstract

An efficient organocatalytic reaction using 1,3-nitro enynes with 4-hydroxycoumarin and 4-hydroxy-6-methyl-2-pyrone to afford pyrano-annulated scaffolds in high yield (up to 88% yield) and excellent stereoselectivities (up to >20:1 dr and >99% ee) is described. The reaction proceeded through sequential conjugate addition, allene formation, intramolecular oxa-Michael 6-endo-dig cyclization and DABCO-catalyzed olefin isomerization. A kinetic profile for isomerization was established. The mechanism for the organocascade reaction was proposed according to requisite computational and mechanistic experimental studies.

Original languageEnglish
Pages (from-to)3098-3101
Number of pages4
JournalOrganic Letters
Volume18
Issue number13
DOIs
Publication statusPublished - 2016 Jul 1

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Cyclization
Alkenes
Isomerization
isomerization
alkenes
Stereoselectivity
synthesis
Scaffolds
Kinetics
kinetics
profiles
propadiene
4-hydroxycoumarin
4-hydroxy-6-methyl-2-pyrone
triethylenediamine

ASJC Scopus subject areas

  • Biochemistry
  • Physical and Theoretical Chemistry
  • Organic Chemistry

Cite this

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title = "Organocascade Synthesis of Annulated (Z)-2-Methylenepyrans: Nucleophilic Conjugate Addition of Hydroxycoumarins and Pyranone to Branched Nitro Enynes via Allene Formation/Oxa-Michael Cyclization/Alkene Isomerization Sequence",
abstract = "An efficient organocatalytic reaction using 1,3-nitro enynes with 4-hydroxycoumarin and 4-hydroxy-6-methyl-2-pyrone to afford pyrano-annulated scaffolds in high yield (up to 88{\%} yield) and excellent stereoselectivities (up to >20:1 dr and >99{\%} ee) is described. The reaction proceeded through sequential conjugate addition, allene formation, intramolecular oxa-Michael 6-endo-dig cyclization and DABCO-catalyzed olefin isomerization. A kinetic profile for isomerization was established. The mechanism for the organocascade reaction was proposed according to requisite computational and mechanistic experimental studies.",
author = "Ramani Gurubrahamam and Gao, {Bing Fong} and Chen, {Yan Ming} and Chan, {Yu Te} and Ming-Kang Tsai and Kwunmin Chen",
year = "2016",
month = "7",
day = "1",
doi = "10.1021/acs.orglett.6b01265",
language = "English",
volume = "18",
pages = "3098--3101",
journal = "Organic Letters",
issn = "1523-7060",
publisher = "American Chemical Society",
number = "13",

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TY - JOUR

T1 - Organocascade Synthesis of Annulated (Z)-2-Methylenepyrans

T2 - Nucleophilic Conjugate Addition of Hydroxycoumarins and Pyranone to Branched Nitro Enynes via Allene Formation/Oxa-Michael Cyclization/Alkene Isomerization Sequence

AU - Gurubrahamam, Ramani

AU - Gao, Bing Fong

AU - Chen, Yan Ming

AU - Chan, Yu Te

AU - Tsai, Ming-Kang

AU - Chen, Kwunmin

PY - 2016/7/1

Y1 - 2016/7/1

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AB - An efficient organocatalytic reaction using 1,3-nitro enynes with 4-hydroxycoumarin and 4-hydroxy-6-methyl-2-pyrone to afford pyrano-annulated scaffolds in high yield (up to 88% yield) and excellent stereoselectivities (up to >20:1 dr and >99% ee) is described. The reaction proceeded through sequential conjugate addition, allene formation, intramolecular oxa-Michael 6-endo-dig cyclization and DABCO-catalyzed olefin isomerization. A kinetic profile for isomerization was established. The mechanism for the organocascade reaction was proposed according to requisite computational and mechanistic experimental studies.

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