Alternative to Diethyl- malonate, permitting removal of the t-butyl groups and decarboxylation by thermolysis in the presence of mild acid: J. Am. Chem. Soc., 74, 831 (1952). In the presence of Cu(OAc)2, condenses with paraformaldehyde to form the useful electrophilic alkene, di-t-butyl methylenemalonate: J. Org. Chem., 48, 3603 (1983), which is more stable than the ethyl or methyl esters, and can be stored for some weeks at room temperature. For references to use of methylenemalonic esters in Michael addition and cycloaddition reactions, see: Org. Synth. Coll., 7, 142 (1990).
