H-1-NMR ANALYSIS OF ISOMERIC 2'(3')-O-TRIALKYLSILYL AND 2'(3')-O-METHYL RIBONUCLEOSIDES

Resonances of ribose moieties of both 2'(3')-O-trialkylsilyl and 2'(3' )-O-methyl isomers of 5'-O-dimethoxytrityl-N-protected ribonucleosides were assigned by H-1, H-1 COSY. The upfield shift of the H-2' or H-3' signal indicates the O-methylation site. The difference in chemical s hifts of methyl protons of the 1-butyl-dimethylsilyl protective group allows assignment of the position of the O-trialkylsilyl substituent. For the latter the Si-29 NMR data are also presented.