Downfield γ‐gauche and γ‐antiperiplanar effects on ¹³C NMR chemical shifts exerted by thiophene sulphur

Abstract

The y-effects of sulphur on "C NMR chemical shifts have been measured in a series of steroidal compounds containing thethiopheneringindifierent configurationswithrespectto therest of themolecule.Thedataconstitute the first example of downfield effects exerted by sulphur on both gauche and antiperiplanar y-carbons. The y-gauche effect of sulphur amounts to 1.6-1.8 ppm, the y-antiperiplanar effect from practically zero to almost 1 PPm*