Meldrum's Acid - Alkylation and Acylation

Alkylation and Acylation

The position between the two carbonyl groups in Meldrum's acid is acidic, allowing simple alkylation and acylation at this position. For example, deprotonation and reaction with a simple alkyl halide allows formation of products containing carbon chains attached to the ring. Alternatively, this position can be acylated with a carboxylic acid chloride (RCOCl).

These two reactions allow Meldrum's acid to serve as a starting scaffold for the synthesis of many different structures with various functional groups. Paired with the pyrolysis and nucleophilic trapping reaction, above, the alkylated products can be carried on to produce a range of different amide and ester compounds. Heating the acyl product in the presence of an alcohol leads to ester exchange and decarboxylation in a process similar to the malonic ester synthesis. The reactive nature of the cyclic-diester allows good reactivity even for alcohols as hindered as t-butanol. Ketoesters of this type are useful in the Knorr pyrrole synthesis.