¹³C, ¹H long‐range coupling constants in configuration assignment of some trisubstituted alkenes

Abstract

Abstract Chemical shifts and long‐range 13 C, 1 H coupling constants to the two carbonyl C atoms were determined for a series of ethyl 2‐acyloxy‐2‐alkenoates. The 3 J (C,H) coupling constant across the double bond is 9.5–10.1 Hz for the E ‐ and 2.9–3.8 Hz for the Z ‐isomer. 3 J (C,H) values, therefore, may be used as a criterion for E/Z differentiation even if only one isomer is available. 13 C chemical shift data, in contrast, cannot be employed for a straightforward differentiation.