bistrimethylsilylamide

Bistrimethylsilylamide, also known as bis(trimethylsilyl)amide, refers to the anion [N(SiMe3)2]− and its metal salts, most commonly lithium bis(trimethylsilyl)amide (LiN(SiMe3)2, often abbreviated LHMDS). These compounds are among the strongest non-nucleophilic bases used in organic synthesis, capable of deprotonating a range of substrates to give carbanions and enolate equivalents under relatively mild conditions. The bulky two trimethylsilyl groups suppress nucleophilic character, allowing selective deprotonation of substrates that are less accessible to other bases.

The salts LiN(SiMe3)2, NaN(SiMe3)2, and KN(SiMe3)2 are typically prepared by deprotonation of hexamethyldisilazane (HMDS) or via metathesis routes, and are commonly employed as dry solids or as solutions in polar aprotic solvents such as THF, diethyl ether, or DME. They are highly sensitive to moisture and air, requiring handling under inert atmosphere.

Applications of bistrimethylsilylamide include generation of carbanion equivalents for subsequent electrophilic trapping, metallation of arenes and heterocycles, and preparation of various organometallic intermediates. Due to their non-nucleophilic nature, they are often preferred for deprotonations of substrates that resist other bases, enabling methods for carbon–carbon bond formation and complex molecule construction.

Safety and handling considerations are important: these bases should be used under inert gas with anhydrous solvents, and stored in dry conditions. Hydrolysis with water or oxygen yields the neutral bis(trimethylsilyl)amine (HN(SiMe3)2) and corresponding metal hydroxide.