Amphiphilic Carbohydrate-Based Mesogens, 12 [1] High-Yield Synthesis of Mesogenic 1-O-Alkanoyl-D/L-Xylitols

The equilibrium mixture of 1,2:3,4- and 1,3:2,4-di-O-ethylboranediyl-D/L-xylitols 1 and 1′ obtained on reaction of three equivalents of xylitol with two equivalents of triethylboroxin, reacts with alkanoyl chlorides (heptanoyl-dodecanoyl) to give equilibrium mixtures of the O-ethylboranediyl protected l-O-alkanoyl-D.L-xylitols 2,2′ after vacuum distillation. Deprotection of the latter affords the title amphiphilic esters 3 which melt to give the smectic A liquid-crystalline phase.