Search

A series of 2-(acetamide-2-yl)-imidazolines (II) with 5 points of diversity were prepared by an Ugi-4CR–Staudinger–aza-Wittig-sequence starting from simple azidoalkylamines. The intramolecular aza-Wittig cyclization between the iminophosphane and the tertiary amide of the Ugi product (I) was effected by short microwave irradiation. Competitive cyclization to the secondary amide was not relevant, however, in some cases subsequent formation of the bicyclic ortho -amidines (III) was observed.

Tetramic acid derivatives constitute an important class of nitrogen containing heterocycles, and are key structural motifs in many natural products of terrestrial and marine origin. The interesting biological and structural diversity of this class of substances makes it a particularly interesting template for the design of compound libraries in search of small molecules that effect cellular signalling pathways. Therefore, a novel combinatorial synthesis of tetramic acids by an Ugi/Dieckmann condensation is described.