p-Tolyl [2-(trimethylsilyl)ethynyl] sulfone (1-tosyl-2-(trimethylsilyl)acetylene) may be used as a reactant in the synthesis of Cp(OC)2M-C=CSiMe3(M = Fe, Ru) by reacting with [Cp(OC)2M ]-Na+and as a reagent in the photochemical alkynylation of unreactive C (sp3)–H bonds.