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29 Si NMR spectra of trimethylsilyl and tert ‐butyldimethylsilyl derivatives of purines and pyrimidines
Author(s) -
Schraml Jan,
Kvíčalová Magdalena,
Blechta Vratislav,
Řeřicha Roman,
Rozenski Jef,
Herdewijn Piet
Publication year - 1998
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/(sici)1097-458x(199801)36:1<55::aid-omr211>3.0.co;2-s
Subject(s) - chemistry , chemical shift , trimethylsilyl , nmr spectra database , silylation , moiety , nucleobase , spectral line , nucleic acid , coupling constant , nuclear magnetic resonance spectroscopy , computational chemistry , stereochemistry , organic chemistry , dna , biochemistry , physics , particle physics , astronomy , catalysis
Trimethylsilyl and tert ‐butyldimethylsilyl derivatives of naturally occurring purines and pyrimidines and also other closely related model compounds were prepared and their 29 Si NMR spectra measured. Only the chemical shifts of the Si—NH— moiety could be assigned experimentally (i.e. exactly); the chemical shifts of Si—O— and Si—N— fragments could be assigned only on the basis of chemical shift correlations. The Si—N— lines are surprisingly narrow in all derivatives of nucleic bases studied. The lines are narrow because of the ‘self decoupling’ of fast relaxing 14 N nuclei. The values of 29 Si, 15 N coupling constants could not be reliably determined (by the HEED–INEPT method), nor could the Si—N lines be completely assigned in these compounds. Measurement of 29 Si NMR spectra is shown to be a sensitive and fast method for checking completeness of silylation of nucleobases or their analogues. Assignment difficulties limit other applications. © 1998 John Wiley & Sons, Ltd.