Unusually large deuterium isotope effects on one‐bond ¹³C, ¹H coupling constants in trans‐stilbene challenged

The reported apparent large decrease in 1 J (C‐α, H‐α) by 1.75±0.20 Hz on replacement of one of the olefinic protons by deuterium in trans ‐stilbene is due to improper first‐order analysis of the 1 H‐coupled 13 C spectrum of the parent compound. Consequently, the implied conformational difference between trans ‐stilbene and α‐deuterio‐ trans ‐stilbene, which was used to explain the result, is not substantiated.