The cycloacylation — 1,3‐Acylrearrangement sequence as tool for highly substituted pyrrolones

The cyclization reactions between bis ‐imidoylchlorides 1 and ketones, which possess different CH‐acidity, were investigated. Diphenylacetone 2 reacts under mild conditions via C,O‐cyclization of the preformed enolate to yield the iminofurane derivative 3 . Upon treatment with trifluoroacetic acid, the latter can be rearranged quantitatively into the pyrrolone 5 . In contrast, 1,3‐acetonedicarboxylate 9 and cyclohexanone 12 immediately lead to highly substituted pyrrolones 11 and 14 . Obviously, the primarily formed cyclization products undergo a very fast 1,3‐acyl rearrangement (Dimroth‐/Mumm‐Rearrangement). The structures of the maleiimide 11 and the indolone 14 were determined by single crystal X‐ray structure analysis. Due to its amino/imino substructure, compound 3 is an efficient ligand for metal complexation reactions, exemplified by the synthesis of two different Zn‐complexes 7 and 8 .