Structure and lipophilicity profile of 2,3-anhydro-alpha-cyclomannin and its ethanol inclusion complex

Readily available from alpha-cyclodextrin in three steps, 2,3-anhydro-alpha -cyclomannin composed of six alpha-(1-->4)-linked 2,3-anhydro-D-mannopyrano se residues, crystallizes well when precipitated from aqueous ethanol. An X -ray structure reveals the macrocycle to contain ethanol in its cavity, thu s representing the first inclusion complex of a non-glucose cyclooligosacch aride. The wider rim of the torus-shaped macrocycle holds the six epoxide r ings whose oxygens point away from the cavity, thereby sculpturing the uniq ue over-all shape of a six-pointed star.