Synthesis of 9H‐Indeno[1,2‐b]Thieno[2,3‐e]Pyridin‐9‐One System Based on Multicomponent Reaction of 3‐Aminothiophenes With Aldehydes and 1,3‐Indandione

For the first time, the multicomponent reaction of 3‐aminothiophenes with various aldehydes and 1,3‐indandione was studied. The unstable starting 3‐aminothiophenes were generated in situ from the corresponding sodium salts of 3‐aminothiophene‐2‐carboxylic acids. We have shown that the considered interaction allows us to construct the 9 H ‐indeno[1,2‐ b ]thieno[2,3‐ e ]pyridin‐9‐one system. A straightforward, one‐step approach to a wide range of target polycyclic products was developed based on the presented multicomponent condensation. Using this method, 21 examples of substituted 9 H ‐indeno[1,2‐ b ]thieno[2,3‐ e ]pyridin‐9‐ones were obtained with yields of up to 76%. The advantages of the designed synthetic route are atom economy, readily accessible starting materials, and a convenient procedure for the isolation of final compounds, avoiding chromatography. The structure of one of the prepared 9 H ‐indeno[1,2‐b]thieno[2,3‐ e ]pyridin‐9‐ones was unambiguously proved using x‐ray diffraction.