NMR spectra are reported for an acetylenic ketone enriched with 13C in the acetylenic carbon atoms that exhibits extremely strong C‐C coupling. Chemical shifts and coupling constants have been extracted from computer simulations of the second‐order 1H and 13C spectra. The two acetylenic carbon atoms exhibit a Δ ν/J ratio of 0.2. Owing to the strong coupling, the double‐quantum coherence 13C spectrum requires an unusually long (58 ms) interpulse delay time in order to obtain a good spectrum. NMR spectra of this compound provide a unqiue example of strong coupling in a CCH (AB or ABX) spin system.
- AB/ABX spin system
- INADEQUATE acetylenic ketones
- strong carbon‐carbon coupling