Acyl-l,5-dihydro-4-hydroxy-2-pyrrolones

Anions of tetramic acids show, as expected, only limited nucleophilic properties. Indeed, O-alkylation requires strongly alkylating agents. Acylation preferentially gives 4-acyloxy-l,5-dihydro-2-pyrrolones which, in the presence of Lewis acids, may undergo rearrangement to 3-acyl-l,5-dihydro-4-hydroxy-2-pyrrolones (Section III). 

Z) is provided in Section II. Section III deals with the rntyor reactions of 3-acyl-l,5-dihydro-4-hydroxy-2-pyrrolones (Y), compounds representing a wide variety of natural substances. Finally, Section IV presents an overview on the chemistry of the actual tetramic acids (X). 

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