Synthesis of oxaloacetic esters

The present review is devoted to oxaloacetic esters widely used in the synthesis of heterocyclic compounds and malonic ester derivatives. Three carbonyl groups of oxaloacetic esters have different reactivity allowing the tuning of overall reactivity of these compounds. The synthetic approaches to oxaloacetic esters, in particular the condensation of oxalates and acetates as well as the modern innovations in this classical synthesis that involved alkyl oxalyl chlorides, are reviewed. The main strategies for modification of oxaloacetic esters, e.g., halogenation and arylation, as well as the possibilities to overcome the side reactions are considered in detail. Special attention is paid to transformations of hydroxysuccinic esters and their oxidation to oxaloacetic esters. The reactions of acetylenedicarboxylic esters with carbonyl compounds, N- and S-oxides, and nitrones are also considered. The mechanisms of the rearrangement of the adducts of acetylenedicarboxylic ethers with heteroaromatic N-oxides are thoroughly discussed.