Studies with condensed amino‐thiophenes: Further investigation of reactivity of amino‐thieno‐coumarines and amino‐thieno‐benzo[h]coumarines toward electron‐poor olefins and acetylenes

The reaction of 3‐amino‐5‐oxa‐2‐thia‐cyclopenta[a]naphthalene‐4‐one 2b with substituted acetylenes afforded C‐1 alkylation products. On the other hand, reaction of 17‐amino‐15‐methyl‐11‐oxa‐16‐thiacyclopenta[a]phenanthrene‐12‐one 5 with substituted acetylenes and electron‐poor olefins afforded the condensed thienopyridine derivatives 7 and 11a–c. The reaction of 5 with acrylonitrile and with 4‐phenyl‐1,2,4‐triazoline‐3,5‐dione afforded compounds 13 and 21 with loss of H2S via the expected [4 + 2] cycloaddition sequence.