13C NMR study on peracetylated derivatives of cyclomaltoheptaose (β-cyclodextrin, β-CD) and its methylated derivative

Abstract

Peracetylated samples of cyclomaltoheptaose (β-cyclodextrin, β-CD) and its methylated derivative were studied by 13C NMR. The acetyl carbonyl carbon signal in peracetylated β-CD was resolved into a triplet, and the three peaks were assigned by long-range CH COSY and INAPT techniques. The individual carbonyl peak was found to be indicative of the location of the acetyl group on the 2, 3, and 6 position in the glucose residues. An acetylated derivative of a partly methylated β-CD was also subjected to 13C NMR analysis to determine the distribution of acetyl and, subsequently, methyl groups on the glucose residues.