Attached Nitrogen Test by C-N Solid-State NMR Spectroscopy for the Structure Determination of Heterocyclic Isomers.

Differentiation of heterocyclic isomers by solution H, C, and N NMR spectroscopy is often challenging due to similarities in their spectroscopic signatures. Here, C{N} solid-state NMR spectroscopy experiments are shown to operate as an "attached nitrogen test", where heterocyclic isomers are easy to distinguish based on one-dimensional nitrogen-filtered C solid-state NMR. We anticipate that these NMR experiments will facilitate the assignment of heterocyclic isomers during synthesis and natural product discovery.