• Title/Summary/Keyword: Umpolung

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Expeditious Synthesis of Natural Benzofuran, Eupomatenoid-6 by Umpolung of α-Aminophosphonates

  • Damodar, Kongara;Jun, Jong-Gab
    • Bulletin of the Korean Chemical Society
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    • v.35 no.12
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    • pp.3618-3622
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    • 2014
  • Simple and practical synthesis of natural benzofuran derivative eupomatenoid-6 via Horner-Emmons type condensation as the key step is described. The umpolung property of aldehyde derivative, ${\alpha}$-aminophosphonate was efficiently employed in this reaction. ${\alpha}$-Aminophosphonate of anisaldehyde subjected to Horner-Emmons type condensation with 5-bromo-2-methoxybenzaldehyde to yield the deoxybenzoin, which was further methylated and then underwent tandem demethylation-cyclodehydration to afford the benzofuran scaffold in excellent yield. Finally Suzuki coupling with propenyl boronic acid afforded eupomatenoid-6 with an overall yield of 56.8%.

Novel Synthesis of 3-Phenyl-chromen-4-ones Using N-Heterocyclic Carbene as Organocatalyst: An Efficient Domino Catalysis Type Approach

  • Mishra, Priya;Singh, Sarita;Ankit, Preyas;Fatma, Shahin;Singh, Divya;Singh, Jagdamba
    • Bulletin of the Korean Chemical Society
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    • v.34 no.4
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    • pp.1070-1076
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    • 2013
  • Herein is reported a simple and efficient synthesis of isoflavones starting from various substituted phenacyl bromides and salicylaldehydes in presence of NHC. The mechanism involved domino catalysis type approach with consumption and regeneration of catalyst in two catalytic cycles. This method proved to be very lucrative and gives very good yield. The method described here represents an environmentally benign alternative to classical approach.