R3SiOR

R3SiOR denotes a class of organosilicon compounds known as silyl ethers, formed when an alcohol ROH is converted to a silicon–oxygen bond. In this representation, the silicon atom bears three organic substituents (the R3Si moiety) and is bonded to an alkoxy group (OR) derived from the protected alcohol. R3SiOR itself is not a single molecule but a general formula used to describe many different silyl-protected alcohols.

Silyl ethers are widely used as protecting groups for alcohols in organic synthesis because they can be installed under mild conditions and removed selectively, allowing stepwise progression of complex sequences. The choice of substituents on silicon (the R groups) affects stability to acids, bases, and moisture, as well as ease of removal.

Common protecting groups include trimethylsilyl (TMS), triethylsilyl (TES), tert-butyldimethylsilyl (TBS), and tert-butyldiphenylsilyl (TBDPS).

Installation generally involves reaction of ROH with a silyl chloride (R3SiCl) or a silyl triflate (R3SiOTf) in the presence of a base such as imidazole or pyridine. Deprotection usually uses fluoride reagents (such as tetrabutylammonium fluoride, TBAF, or HF-pyridine) or, for some groups, mild acid. The most bulky silyl ethers tend to be more resistant to both acid and fluoride-mediated cleavage than smaller ones like TMS.

Applications span many areas of organic synthesis, including selective protection of diols and complex natural product and carbohydrate syntheses. They enable differential protection strategies in multi-step sequences, with stability and deprotection conditions tuned by the choice of the R groups on silicon.