γ‐Al₂O₃/triflic acid as cooperative catalysts for the tandem Michael addition/carbocyclization: An easy access to 2‐substituted pyrrolo[2,1‐a]isoquinolines and 3‐substituted pyrrolidine‐2,5‐diones

Abstract

A tandem Michael addition/carbocyclization of 3,4-dimethoxyphenethyl maleimide with carbon and sulfur nucleophiles is accomplished via a relay catalysis using γ-Al 2 O 3 /TfOH binary system. The X-ray Photoelectron Spectroscopy (XPS) analysis of binary system indicates the presence of AlF 3 , AlO(OH) species . This approach provides an easy access to 2-aryl or 2-thio aryl pyrrolo[2,1-a]isoquinolines in good yields in a tandem fashion. With suitable ratio of γ-Al 2 O 3 /TfOH binary system, the Michael addition of N/C/S nucleophiles to N-benzyl maleimide is also achieved. A key to the success of these reactions would be the generation of AlF 3 , AlO(OH) species from γ-Al 2 O 3 and TfOH, which might have delineated the disadvantageous background reactions usually displayed by a strong Brønsted acid such as TfOH.

Synthesis of some pyrrolidine‐2,5‐dione derivatives with biological activity against Gram‐negative bacteria

“…[ 1‐4 ] It is noteworthy that pyrrolidine‐2,5‐diones derivatives are an important class of heterocyclic compounds which have different applications in medicinal chemistry. [ 5‐7 ] Several pyrrolidine‐2,5‐diones have been prepared for therapeutic purposes such as diabetes, [ 8 ] inflammation, [ 9 ] epileptic, [ 10 ] cancer, [ 11 ] pain, [ 12 ] depression [ 13 ] and infectious. [ 14 ] For example, a pyrrolidine 2,5‐dione derivative was synthesized from indole, benzaldehyde and succinimide as antibacterial agent against Escherichia coli .…”