13C-Labeling as an effective tool to study ring transformations and to facilitate structural elucidation of nitrogen heterocycles by 13C NMR spectroscopy

Abstract

This review focuses on the effective application of ¹³C NMR characteristics of ¹³C-labeled heterocyclic compounds [chemical shifts of ¹³C labeled carbon, analysis of direct and long-range ¹³C-¹³C coupling constants (J_CC)] in structure elucidations, determinations of mechanisms and pathways of transformation in series of azole, azine and N-heterocyclic carbenes. Moreover, incorporation methods of ¹³C isotopes into structures of different heterocyclic compounds are provided in this review.