Synthesis of isomeric enamine derivatives of fused cycloalkeno thieno[2,3-d]pyrimidin-4(3H)-ones. Stereoelectronic effect on the regioselectivity

Annarnaria Lilienkampf*, Sami Heikkinen, Ilpo Mutikainen, Kristiina Wahala, Annamaria Lilienkampf

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

A regioselective synthesis of enamine and enaminone derivatives of fused cycloalkeno thieno[2,3-d]pyrimidin-4(3H)ones is reported. The enamine versus enaminone product in the condensation reaction with N,N-dimethylformamide dimethylacetal (DMFDMA) was shown to depend on the conformation of the cycloalkeno ring fused to the pyrimidinone moiety. The ring conformation and the stereoelectronic effect of the amidine a-protons were studied by X-ray crystallography. In deuterium exchange experiments, the amidine-ketene-N,N-acetal tautomerism was shown to be prohibited with larger (n = 3-4) ring systems consequently yielding the enaminone products.

Original languageEnglish
Pages (from-to)2699-2705
Number of pages7
JournalSynthesis: Journal of Synthetic Organic Chemistry
Issue number17
DOIs
Publication statusPublished - 3 Sep 2007

Keywords

  • regioselectivity
  • electrophilic additions
  • imines
  • ketones.
  • tautomerism
  • SOLID-PHASE SYNTHESIS
  • LACTIM ETHERS
  • FUNCTIONALIZED 2-PYRIDONES
  • PARALLEL SYNTHESIS
  • PYRROLES
  • KETONES
  • 2-DIMETHYLAMINOMETHYLENE-1,3-DIONES
  • DINUCLEOPHILES
  • PYRIMIDINES
  • PIPERIDINES

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