It is often difficult to unambiguously determine structures of molecules, which have many non-protonated carbon atoms. Because such compounds contain quaternary carbons, lack protons and bonding to quaternary carbons each other, HMBC (Heteronuclear Multiple Bond Correlation) experiment cannot provide long-range 1H-13C connectivity. Therefore, INADEQUATE (Incredible Natural Abundance DoublE QUAntum Transfer Experiment), which is 13C-13C correlation experiment at natural 13C abundance, represents a powerful tool for proton-diluted compounds.