[13C and 1H NMR of (1 goes to 6)-beta-D-glucan, linear oligosaccharides and their corresponding cyclic forms].

The results of 1H-n.m.r. and 13C-n.m.r. studies of linear and cyclic oligosaccharides in the series of gentiodextrins, both in their hydroxylated and acetylated form, were compared to those obtained for the corresponding natural or synthetic polysaccharide. The 13C-signals of each D-glucopyranose unit of acetylated oligosaccharides are more distinct than those of the parent hydroxylated compounds. In order to relate the change of the various signals with the degree of polymerization, gentiotriose undecaacetate, enriched in 13C at C-1'', was prepared, as well as gentiotetraose tetradecaacetate selectively labeled at C-1'' and C-1'''. A (1 leads to 6)-beta-D-glucan having a D.P. of approximately 10 was chemically prepared. During the course of the polycondensation, the 2,3,4,2',3',4'-hexa-O-acetyl-di-beta-D-glucopyranosyl 1,6':6,1'-dianhydride, and the 2,3,4,2',3',4',2'',3'',4'',2''',3''',4'''-dodeca-O-acetyl-tetra-beta-D-glucopyranosyl 1,6''':6,1'''-tetraanhydride, respectively, were formed.