A simple and expedient method for the synthesis of ethyl 3‐amino‐4,6‐diarylthieno[2,3‐b]pyridine‐2‐carboxylate

Abstract

1 was reacted with ethyl 2-mercaptoacetate 2 to furnish ethyl 2-(3-cyano-4,6-diarylpyridin-2-ylthio)acetate 3 as intermediates. These intermediates were cyclized by Thorpe-Zeigler cyclization using solid-liquid phase-transfer catalysis conditions to give ethyl 3-amino-4,6-diarylthieno[2,3-b]pyridine-2-carboxylate 4. One-pot heterocyclization without isolating the intermediates was also achieved using solid-liquid phase transfer conditions.

Recent advances in the chemistry of thieno[2,3-b]pyridines 1. Methods of synthesis of thieno[2,3-b]pyridines

“…The cyclocondensation of 2-chloronicotinonitriles with HSCH 2 CO 2 Et in the presence of fi nely ground KOH under phase transfer catalysis conditions was studied. 136 It is interesting to note that when triethylbenzylammonium chloride (TEBA) was used, the reaction stopped at the stage of nicotinonitriles 65, while cyclization products 66 were formed in the presence of 18-crown-6 (Scheme 26).…”