Trityl derivatives of cellobiose. VI. Unambiguous assignments of acetoxyl group resonances in the 1H-NMR spectra of 6,6'-di-O-trityl-, 6-O-trityl-, and 6'-O-tritylcellobiose peracetates.

Abstract

The 1H-NMR spectra of 6, 6'-di-O-trityl-, 6-O-trityl-, and 6'-O-tritylcellobiose peracetates (I-1, II-1, and III-1) showed some of the acetoxyl group resonances at abnormally high fields in CDCl3 and all their acetoxyl group signals were resolved in the region of δ 1.56-2.16. Each individual acetoxyl group signal in the spectra was unambiguously assigned. For this purpose, analogs having trideuterioacetoxyl groups at specific positions were synthesized. The 2'-acetoxyl group exposed to the benzene nuclei of the triphenylmethoxyl group (TrO) at C-6 resonates at the highest field. The large upfield shifts of the 4'- and 3-acetoxyl group signals of the derivatives having TrO at C-6' suggest that there are strong interactions between those acetoxyl groups and TrO. In the spectra of the derivatives which have TrO at C-6, a downfield shift of the 1-acetoxyl group signal was observed.