The quantitative measurement of long-range proton-carbon coupling constants for small and medium-size organic compounds at natural abundance has been an interesting topic among the years. From the values of theses coupling constants, dihedral angles can be characterized by means of Karplus-type relationships ( 76PROG41 ). NMR methods to perform such measurements can be summarized as:

Carbon-detected 1D 2D

Proton-Detected Selective 1D Inverse 2D Inverse

Application nJ(CH) nJ(NH) nJ(FH) Spectra: Examples