Assignment of chemical shifts in benzohydroxamic acid and structure of its silylated derivatives by 15N enrichment
✍ Scribed by Jan Schraml; Vratislav Blechta; Ludmila Soukupová; Jindřich Karban; Jaromír Mindl
- Publisher
- John Wiley and Sons
- Year
- 2003
- Tongue
- English
- Weight
- 99 KB
- Volume
- 41
- Category
- Article
- ISSN
- 0749-1581
- DOI
- 10.1002/mrc.1217
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✦ Synopsis
Abstract
^15^N isotopic enrichment was necessary for the unequivocal assignment of the ^1^H NMR lines to the protons in the NH–OH fragment of benzohydroxamic acid, BHXA, C~6~H~5~CONHOH, in dry dimethyl sulfoxide solutions. The assignment [δ(NH) = 11.21, δ(OH) = 9.01, ^1^J(^15^N,^1^H) = 102.2 Hz, ^2^J(^15^N,^1^H) <1.5 Hz], which is opposite to that used by other authors, confirms the assignment extended to BHXA by Brown and co‐workers from the spectra of acetohydroxamic acid. The enrichment allowed also assignment of the ^29^Si lines in the spectra of disilylated benzohydroxamic acid, (Z)‐tert‐butyldimethylsilyl N‐tert‐butyldimethylsilyloxybenzoimidate (2) and (Z)‐tert‐butyldiphenylsilyl N‐tert‐butyldiphenylsilyloxybenzoimidate (3), and confirmed structure of the monosilylated products, N‐tert‐butyldiphenylsilyloxybenzamide (4) and N‐tert‐butyldiphenylsilyloxy benzoimidic acid (5). Copyright © 2003 John Wiley & Sons, Ltd.