Dealkoxycarbonylations of activated esters

Dealkoxycarbonylation of activated esters occurs classically under drastic thermal conditions [90]. It constitutes a typical example of a very slow-reacting system (with a late TS along the reaction coordinates) and is therefore prone to a microwave effect. The rate determining step involves a nucleophilic attack by halide anion and requires anionic activation, which can be provided by solvent-free PTC conditions under the action of microwave irradiation [91]. The above results illustrate the difficult example of cyclic /1-ketoesters with a quaternary carbon atom in the a position relative to each carbonyl group (Eq. 36). 

Dealkoxycarbonylation of malonate esters, p-keto esters and a-cyano esters or other activated esters in dipolar aprotic solvents in the presence of an equiv. of water or of water with added salts. 

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