Studies of the π‐electron distribution in push–pull alkenes by ¹H and ¹³C NMR spectroscopy—II

Abstract

Abstract A wide variety of push–pull alkenes were studied by means of variable‐temperature 1 H and 13 C NMR spectroscopy with respect to the configuration/conformation and the barriers to rotation about partial CC and CN double bonds. For the assignment of the 13 C NMR spectra especially the semi‐selective INEPT pulse sequence and an incremental system for estimating the 13 C chemical shift values of aromatic carbon atoms proved useful. The influence of thioether, sulphone and sulphoxide moieties in the acceptor part of the push–pull system on the π‐electron distribution is critically considered.