Preparation of new nitrogen-bridged heterocycles 72. A new approach to 1-acyl-3-(substituted methylthio)thieno[3',4':4,5]imidazo[1,2-a]pyridine derivatives. [corrected]

Chem Pharm Bull (Tokyo). 2010 Nov;58(11):1502-10. doi: 10.1248/cpb.58.1502.

Abstract

The alkaline treatment of the pyridinium salts, readily available from the S-alkylations of 3-amino-4-(1-pyridinio)thiophene-5-thiolates with various alkyl halides, in chloroform at room temperature afforded the corresponding thieno[3',4':4,5]imidazo[1,2-a]pyridine derivatives in low to moderate yields via the intramolecular cyclization of the resulting 1,5-dipoles followed by the aromatization of the primary cycloadducts. Interestingly, the reactions using unsymmetrical 3-amino-4-[1-(3-methylpyridinio)]thiophene-5-thiolates afforded only 8-methylthieno[3',4':4,5]imidazo[1,2-a]pyridines and the other 6-methyl derivatives were not formed at all. In addition the isolation of a byproduct in the condensation reaction of pyridinium salt with the solvent (CHCl₃) is also discussed.

MeSH terms

  • Heterocyclic Compounds / chemical synthesis*
  • Heterocyclic Compounds / chemistry
  • Nitrogen Compounds / chemical synthesis*
  • Nitrogen Compounds / chemistry
  • Thienopyridines / chemical synthesis*
  • Thienopyridines / chemistry

Substances

  • Heterocyclic Compounds
  • Nitrogen Compounds
  • Thienopyridines