三甲基乙炔基硅

Trimethylsilylacetylene is an acetylene molecule protected on one end by the trimethylsilyl group. It is popularly used in alkynylations, e.g. the Sonogashira reaction. After desilylation (e.g. with TBAF), the ethynyl group is introduced. Using a protected alkyne, as opposed to acetylene gas, prevents further (undesired) coupling reactions and also has the benefit of being a liquid.
This compound is commercially available. It may also be prepared in a manner similar to other silyl compounds: deprotonation of acetylene with a Grignard reagent, followed by reaction with trimethylsilyl chloride.