Abstract
The present work examines the relationship between the structure and chiroptical properties of penicillins and cephalosporins and their oxa- and carbaanalogues utilizing the electronic circular dichroism (CD). For some of the model compounds the study is additionally supported by the X-ray diffraction analysis. The applicability of the helicity rule that correlates the molecular structure of compounds and their CD spectra in respect to all classes of β-lactam derivatives is tested. It is demonstrated that a variety of oxacephams, clavams, and their carbaanalogues conform to the rule. To validate the experimental data the CD spectra computed using time-dependent density functional theory (TDDFT) are compared to the experimental curves recorded for the representative β-lactam derivatives. The study reveals a high sensitivity of the CD spectra to the configuration at the bridgehead atom and a surprisingly high sensitivity to the molecular conformation and substitution of the five- or six-membered ring. The results demonstrate that such a combined treatment permits the determination of the absolute configuration with high confidence.
Call for Papers in Thematic Issues
Catalytic C-H bond activation as a tool for functionalization of heterocycles
The major topic is the functionalization of heterocycles through catalyzed C-H bond activation. The strategies based on C-H activation not only provide straightforward formation of C-C or C-X bonds but, more importantly, allow for the avoidance of pre-functionalization of one or two of the cross-coupling partners. The beneficial impact of ...read more
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