Total assignment of 1H and 13C spectra of kauradien-9(11),16-oic acid with the aid of heteronuclear correlated 2D spectra optimized for geminal and vicinal 13C–1H coupling constants: or what to do when "INADEQUATE" is impossible

Abstract

It is shown that heteronuclear correlated spectra in which delay times are optimized for geminal and vicinal ¹³C–¹H couplings rather than direct, ¹³C–¹H couplings can be used to assign quaternary carbons in the ¹³C spectrum of kauradien-9(11),16-oic acid. These spectra in combination with normal heteronuclear correlated spectra plus homonuclear correlated spectra can be used to completely and unambiguously assign the ¹³C and ¹H spectral peaks for the title compound. The main advantage of this approach over the use of ¹³C–¹³C connectivity ("INADEQUATE") experiments is sensitivity.