4-Chloro-3-nitrocoumarin as a precursor for synthesis of 2-arylchromeno[3,4-b]pyrrol-4(3H)-ones: a case of nitro
Balasubrahmanya K Sathyanarayana1, Kiran B Manjappa1, Ding-Yah Yang1,2
1Graduate Program for Biomedical and Materials Science, Tunghai University, Taiwan. kiran@thu.edu.tw.
Abstract:
A series of 2-aryl substituted chromeno[3,4-b]pyrrol-4(3H)-ones were prepared in two steps by employing 4-chloro-3-nitrocoumarin as a precursor. The reaction involved the base-mediated reductive coupling of 4-chloro-3-nitrocoumarin with α-bromoacetophenone, followed by reductive intramolecular cyclization to afford the pyrrolocoumarin ring. When α-bromoacetophenone was replaced with α-cyanoacetophenone, (E)-4-(nitromethylene)-4H-chromen-2-amine was isolated as the major product. The molecular structures of the prepared compounds were characterized by X-ray crystallography and the mechanisms for their formation were proposed.
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