ββ-Dimethyl fatty acids are conveniently synthesised by Friedel–Crafts acylation of thiophen and its homologues with ββ-dimethylglutaric anhydride, Wolff-Kishner reduction of the γ-thenoylbutyric acids obtained to the corres-ponding ω-thienylvaleric acids, and hydrogenolysis of the latter with Raney nickel.