trimethylsilylacetylene

Trimethylsilylacetylene is an organosilicon compound with the formula (CH3)3Si–C≡CH. It is the trimethylsilyl-protected derivative of acetylene and is widely used as a versatile building block in organic synthesis. The molecule features a terminal alkyne protected by a bulky, moisture‑sensitive silicon group, which can be removed under fluoride ion conditions to regenerate the free alkyne when needed.

Preparation methods typically involve silylation of acetylene. This can be achieved directly by reacting acetylene or lithium acetylide with chlorotrimethylsilane (TMSCl) in the presence of a base, or by first forming the lithium acetylide and then quenching with TMSCl. These routes provide the protected alkyne in good yields and allow for scalable production.

In terms of properties, trimethylsilylacetylene is a colorless, volatile liquid under ambient conditions that is relatively stable in air but hydrolyzes in the presence of moisture. The TMS group serves as a protective handle for the terminal alkyne, reducing unwanted reactions during multistep sequences. It is typically stored under inert atmosphere and away from moisture.

Applications and reactivity center on its role as a masked terminal alkyne. After deprotection with fluoride sources such as TBAF or HF-pyridine, the liberated acetylene participates in numerous coupling reactions, notably the Sonogashira coupling with aryl or vinyl halides. The TMS group also enables selective or iterative synthesis by postponing alkyne formation until a later stage in a synthetic sequence.