ISSN:
1573-9171
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Conclusions 1. On the basis of the NMR-H1 spectra of methyl esters of benzyl- and phenoxymethylpenicillins, cloxacillin, and methicillin, as well as a number of C(3) derivatives of benzyl- and phenoxymethylpenicillins, the regions of the chemical shifts of the characteristic groups of theβ-lactam-thiazolidine bicyclic system, which might be useful in an investigation of new representatives of this class of compounds, were established (considering the literature data). 2. The side chain influences the chemical shifts of the gem-methyl protons away from it. 3. The spin-spin interaction constant of theβ-lactam protons changes little in the series of investigated compounds, from which it follows that theβ-lactam ring does not undergo any significant conformational changes. 4. The selective broadening of the signals from the protons of the CH2 and C(2) (CH3)2 groups of the methyl esters of benzyl- and phenoxymethylpenicillins when the temperature is lowered is apparently evidence of the formation of inter- or intramolecular complexes, the structure of which is responsible for the decrease in the relaxation time of these groups. 5. The nature of the influence of the side chain on the parameters of the NMR-H1 spectra forces us to assume that in the ground state of the molecule (in inert medium), there is either no specific interaction between theβ-lactam amide group and the side chain, or this interaction is weak and lies outside the limits of detection by the NMR method.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00904022
Permalink