[NMR study on the determination of structure in the protected glucosamineoside]

The protected glucosamines 5, 8, 9, 12, 13 and the protected diglucosamines 10 and 11 were prepared from D-glucosamine hydrochloride, trichloroacetonitrile, trichlorocthoxycarbonyl chloride and trimethylsilyl trifluoromethanesulfonate (TMSOTf). They were new products and their structures were characterized by means of 1H NMR and 13C NMR. The data of 1H NMR indicated that the chemical shift of NH of them were moved remarkably to the low field 5.07-5.26 compared with that of D-glucosamine hydrochloride. The data J(1, 2) of the compounds 9, 10, 11, 12, 13 were between 7.2 and 8.8 Hz, which showed their structures were beta configuration, while the data J(1, 2) were between 3.00 and 4.96 Hz in the compounds 5 and 6, which showed their structures were alpha configuration. H-2 was situated in the higher field, which delta was between 3.10 and 4.30. The data of 13C NMR showed that the delta of C-1 laid in the lowest field and the delta of C-2 laid in the higher field, as were the delta of H-1 and H-2 in NMR. Commonly speaking, if the delta of C-1 was greater than 100, the structure of the compound was beta configuration such as compound 9 (delta = 101.9). On the contrary, if the delta of C-1 was less than 100, the structures were alpha configuration like compound 5 (delta = 95.20) and 6 (delta = 97.21). The chemical shift of other carbon and hydrogen in the ring were discussed. The progression of Carbon in the compound 6 were distinguished conveniently and clearly by using DEPT (Distortionless Enhancement by Polarization Transfer) and 13C NMR.