Malonate ester which is an unusually strong acid (pKa = 9.97) in comparison with, e.g. Diethyl- malonate: J. Am. Chem. Soc., 70, 3426 (1948). The mild conditions required for alkylation, acylation, etc. and the ease with which the products undergo alcoholysis or hydrolysis-decarboxylation make Meldrum's acid a valuable and versatile synthetic intermediate. Reviews: Chem. Soc. Rev., 7, 345 (1978); Heterocycles, 32, 529 (1991); Synlett, 1649 (2004).For phase-transfer alkylation using K2CO3 as base, see: Synthesis, 452 (1982); Bull. Soc. Chim. Belg., 104, 643 (1995). Phase-transfer addition to Michael acceptors also occurs: Synthesis, 224 (1984). Mitsunobu dialkylation with an alcohol and DIAD/Ph3P is also possible: J. Org. Chem., 62, 1617 (1997).
