A variety of SmI₂-promoted electron transfer reactions have been developed for the formation of C-C bonds. They involve (i) palladium catalyzed umpolung of allylic and propargylic acetates, (ii) generation of iodomethyl anion and homo- and bishomoenolate anion intermediates or its synthetic equivalents, (iii) medium-ring lactone formation by Reformatsky-type reaction, (iv) aryl radical cyclization for the formation of heterocycles. (v) masked-formylation via 1,3-dioxolane radical formation, (vi) reductive dimerization of α-bromoesters and conjugated acid derivatives, and (vii) intermolecular ketyl radical alkylation with activated alkenes and alkynes.