Concise Approach towards Tetramic Acid Derivatives via Ugi Reaction/Dieckmann Cyclization Sequence

Tetramic acids exhibit intriguing biological activity and are particularly attractive scaffolds for drug design. In this paper, we present a convenient approach based on the Dieckmann cyclization of Ugi adducts of malonic monoesters to afford a series of medically important polysubstituted tetramic acid derivatives. This simple and versatile method tolerates various substituents in both the amine, aldehyde and isocyanide moieties allowing the use of alpha-substituted malonic acid monoesters. Examples of further functionalization of the free methylene group in the synthesized compounds have been presented. Herein, we present a convenient approach to tetramic acid core formation based on the use of Ugi adducts obtained from monomethyl malonate and various amines, aldehydes, and isocyanides in Dieckmann condensation under mild conditions. When dimethyl substituted monomethyl malonate amides were involved into the reaction, the cyclization was accompanied by decarbamoylation, yielding tetramic acids with the loss of exocyclic amide group. image