DETERMINATION OF LONG-RANGE H-1-C-13 COUPLING-CONSTANTS OF CIS-VERBENOL BY MODIFIED 2D J-SPECTROSCOPY

Known selective 2D J-resolved methods for the determination of long-range proton-carbon coupling constants, (n)J(C,H), have been modified and improved by introducing an INEPT or refocused INEPT sequence as a preparation period in the Bax-Freeman selective spin-flip method, or using exclusively selective pulses from the decoupler channel in the selective INEPT-2D experiment. The greater sensitivity achieved allowed the determination of these couplings, even for quaternary carbons, in a short acquisition time and with excellent reproducibility for cis-verbenol.