LONG-RANGE CARBON PROTON COUPLINGS IN STRYCHNINE

Long-range C-13,H NMR coupling constants were measured in strychnine at 400 MHz by a method that employs selective excitation of individual C-13 sites under decoupled conditions followed by polarization transfer to protons. The sensitivity was improved by performing eight simultaneous soft-pulse experiments coded (+/-) according to a Hadamard matrix and later separated by reference to the same matrix. The antiphase C-13,H splittings were measured by J-doubling performed in the frequency domain.