Novel (2-amino-4-arylimidazolyl)propanoic acids and pyrrolo[1,2-c]imidazoles via the domino reactions of 2-amino-4-arylimidazoles with carbonyl and methylene active compounds

The unexpectedly uncatalyzed reaction between 2-amino-4-arylimidazoles, aromatic aldehydes and Meldrum's acid has selectively led to the corresponding Knoevenagel-Michael adducts containing a free amino group in the imidazole fragment. The adducts derived from Meldrum's acid have been smoothly converted into 1,7-diaryl-3-amino-6,7-dihydro-5H-pyrrolo[1,2-c]imidazol-5-ones and 3-(2-amino-4-aryl-1H-imidazol-5-yl)-3-arylpropanoic acids. The interaction of 2-amino-4-arylimidazoles with aromatic aldehydes or isatins and acyclic methylene active compounds has led to the formation of pyrrolo[1,2-c]imidazole-6-carbonitriles, pyrrolo[1,2-c]imidazole-6-carboxylates and spiro[indoline-3,7'-pyrrolo[1,2-c]imidazoles], which can be considered as the analogues of both 3,3'-spirooxindole and 2-aminoimidazole marine sponge alkaloids. © 2019 Lipson et al.