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]
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.
Department of Chemistry and Material Engineering, Shinshu University, Wakasato, Nagano, Japan. xkakehi@shinshu-u.ac.jp
Akikazu
A
Kakehi
Hiroyuki
H
Suga
Yukihisa
Y
Okumura
Kennosuke
K
Itoh
Kouji
K
Kobayashi
Yoshihiro
Y
Aikawa
Kotaro
K
Misawa
D006571:Heterocyclic Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D017672:Nitrogen Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D058924:Thienopyridines / Q000138:chemical synthesis* / Q000737:chemistry
D006571:Heterocyclic Compounds; D017672:Nitrogen Compounds; D058924:Thienopyridines