13C nuclear magnetic resonance of N-heterocycles. Part 3. 13C Chemical shift assignments of the carbonyl groups in penicillins and cephalosporins
- 1 January 1977
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Perkin Transactions 2
- No. 13,p. 1749-1752
- https://doi.org/10.1039/p29770001749
Abstract
The 13C resonance frequencies of all the carbonyl carbon atoms in several penicillins and cephalosporins have been uniquely assigned for aqueous solutions by use of various experimental techniques. The 13C shift values are compared with other spectroscopic data (i.r. and X-ray). The possibility of interpreting the 13C results in terms of charge density distributions is discussed in relation to the mechanism of ring opening of the β-lactams by basic hydrolysis. For those compounds for which spectra have not been reported previously, the 13C frequencies of all the carbon atoms are assigned.Keywords
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