Gold(III) chloride catalyzed synthesis of chiral substituted 3-formyl furans from carbohydrates: Application in the synthesis of 1,5-dicarbonyl derivatives and furo[3,2-c]pyridine

Kanchan Mal, Abhinandan Sharma, Indrajit Das

Research output: Contribution to journalArticlepeer-review

26 Scopus citations

Abstract

This report describes a gold(III)-catalyzed efficient general route to densely substituted chiral 3-formyl furans under extremely mild conditions from suitably protected 5-(1-alkynyl)-2,3-dihydropyran-4-one using H2O as a nucleophile. The reaction proceeds through the initial formation of an activated alkyne-gold(III) complex intermediate, followed by either a domino nucleophilic attack/anti-endo-dig cyclization, or the formation of a cyclic oxonium ion with subsequent attack by H2O. To confirm the proposed mechanistic pathway, we employed MeOH as a nucleophile instead of H2O to result in a substituted furo[3,2-c]pyran derivative, as anticipated. The similar furo[3,2-c]pyran skeleton with a hybrid carbohydrate-furan derivative has also been achieved through pyridinium dichromate (PDC) oxidation of a substituted chiral 3-formyl furan. The corresponding protected 5-(1-alkynyl)-2,3-dihydropyran-4-one can be synthesized from the monosaccharides (both hexoses and pentose) following oxidation, iodination, and Sonogashira coupling sequences. Furthermore, to demonstrate the potentiality of chiral 3-formyl furan derivatives, a TiBr4-catalyzed reaction of these derivatives has been shown to offer efficient access to 1,5-dicarbonyl compounds, which on treatment with NH4OAc in slightly acidic conditions afforded substituted furo[3,2-c]pyridine.

Original languageEnglish
Pages (from-to)11932-11945
Number of pages14
JournalChemistry - A European Journal
Volume20
Issue number37
DOIs
StatePublished - 8 Sep 2014
Externally publishedYes

Keywords

  • carbohydrates
  • chirality
  • furans
  • gold
  • homogeneous catalysis

ASJC Scopus subject areas

  • Catalysis
  • Organic Chemistry

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