Determination of long‐range ¹H¹³C 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, nJ(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. Copyright © 1992 John Wiley & Sons, Ltd.