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)] for structural elucidation, and for determining mechanisms and transformation pathways in various azoles, azines and N-heterocyclic carbenes. Moreover, this review outlines methods for incorporating ¹³C isotopes into structures of different heterocyclic compounds.