A new strategy for the synthesis of pyridines from N-propargylic beta-enaminothiones


Kelgokmen Y. , Zora M.

ORGANIC & BIOMOLECULAR CHEMISTRY, vol.17, pp.2529-2541, 2019 (Journal Indexed in SCI) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 17
  • Publication Date: 2019
  • Doi Number: 10.1039/c8ob03180k
  • Title of Journal : ORGANIC & BIOMOLECULAR CHEMISTRY
  • Page Numbers: pp.2529-2541

Abstract

A new method for the synthesis of 2,4,5-trisubstituted pyridines from N-propargylic beta-enaminothiones is reported. beta-Enaminothiones were prepared by thionation of the corresponding beta-enaminones with Lawesson's reagent. When treated with diisopropylamine in DMF at room temperature, N-propargylic beta-enaminothiones yielded 2,4,5-trisubstituted pyridines in moderate to high yields, along with small amounts of 2-methylene-2,3-dihydro-1,4-thiazepines. The reaction was found to be general for a broad range of N-propargylic beta-enaminothiones and tolerated the presence of aromatic, heteroaromatic and aliphatic groups with electron-withdrawing and electron-donating substituents. The method could be widened to the internal alkyne-tethered N-propargylic beta-enaminothiones. This operationally simple method may provide rapid access to a library of functionalized pyridines of pharmacological interest.