Inherent Chirality Through a Simple Dialkylation of 2,14-Dithiacalix[4]arene

The dialkylation of 2,14-dithiacalix[4]arene was studied employing various synthetic procedures known for the parent macrocycles (thiacalixarenes and/or classical calixarenes). The best results for distal dialkylation were achieved using Mitsunobu reaction with corresponding alcohols. Interestingly, due to the lower symmetry of the starting compound, the dialkylated derivatives represent inherently chiral systems. The introduction of chiral substituents, thus, leads to mixtures of diastereomers potentially useful for the separation of individual stereoisomers as demonstrated by chiral HPLC. The conformational behavior of novel compounds was studied both in solution (NMR) and in the solid state (X-ray).