5-Alkyl and 5,5-dialkyl Meldrum’s acids (1 and 2, respectively) are used in total synthesis.[1] Monoalkylated derivatives 1 are synthesized from Meldrum’s acid 3 by condensation with aldehyde[2] (or by acylation[3]) followed by hydrogenation. 5,5-Dialkyl Meldrum’s acids 2 can be obtained by alkylation of Meldrum’s acid 3 or its monoalkylated derivatives 1 (Scheme [1]).[4] Herein, reactions of Meldrum’s acids 1 and 2 proceeding with destruction of 1,3-dioxane cycle are reviewed.