Identification and structure elucidation by NMR spectroscopy

• LR-HSQMBC experiment facilitated structure elucidation of H-deficient molecules.
• Ultrafast 2D-NMR acquires a 2D-NMR spectrum in several seconds.
• A pure shift approach dramatically simplified 1H and 2D-NMR spectra interpretation.
• New methods of mixture analysis without any compound separation.
• A CASE expert system is capable of determining manually undecipherable structures.

The state of the art and recent developments in application of nuclear magnetic resonance (NMR) for structure elucidation and identification of small organic molecules are discussed. The recently suggested new two-dimensional (2D)-NMR experiments combined with the advanced instrumentation allow structure elucidation of new organic compounds at a sample amount of less than 10 µg. A pure shift approach that provides 1H-decoupled proton spectra drastically simplified 1H and 2D NMR spectra interpretation. The structure elucidation of extremely hydrogen-deficient compounds was dramatically facilitated due to the methodology based on combination of new 2D-NMR experiments providing long-range heteronuclear correlations with computer-assisted structure elucidation (CASE). The capabilities of CASE systems are discussed. The role of NMR-spectrum prediction in structure verification and NMR approaches for qualitative mixture analysis are considered.