Synthesis and Liquid Crystalline Properties of 5-Alkyl-1,4-dioxane-2-carboxylic­ Esters

The first route to 5-alkyl substituted and purely transconfigurated 1,4-dioxanecarboxylic acids 3 is described. The mesogenic properties of the esters 17 and 20, which are derived from the acids 3 and esters 19 (prepared from the hemiacetal 8a), are studied and compared. An enantioselective route to 1,4-dioxanecarboxylic acid 3a is explained, and takes advantage of the stereoselective addition of the bromolithioalkene 11b to heptanal.