Synthesis of the first per(3-deoxy)-cyclooligosaccharide: hepta(manno-3-deoxy-6-O-t-butyldimethylsilyl)-β-cyclodextrin

Abstract Reduction of hepta( manno -2,3-anhydro-6- O - t -butyldimethylsilyl)-β-cyclodextrin with lithium triethylborohydride gives hepta( manno -3-deoxy-6- O - t -butyldimethylsilyl)-β-cyclodextrin. This compound plus the hepta(2- O -methyl)- and hepta(2- O -benzyl)-derivatives all have the 4 C 1 conformation. Capillary GC columns manufactured with hepta( manno -2,3-anhydro-, hepta( manno -3-deoxy-2- O -methyl- and hepta( manno -2- O -benzyl-6- O - t -butyldimethylsilyl)-β-cyclodextrin stationary phases were evaluated for enantio-discrimination with 39 non-polar racemic analytes. The GC column coated with the benzyl derivative showed enantioselectivity comparable to, and in some cases superior to, a commercial per(methyl)-β-cyclodextrin column. The other columns showed little or no enantio-discrimination. A thermodynamics study established a linear enthalpy–entropy compensation effect for two series of analytes on the commercial permethyl-β-cyclodextrin column, but not for the column coated with the benzyl derivative.