N,N-bis(trimethylsilyl)formamide

UsesN,N-Bis(trimethylsilyl)formamide can be used as source of nucleophilic formamide and N-silylaldimine synthon. N,N-Bis(trimethylsilyl)formamide (BSF) exists in the amide form with both silyl groups attached to the nitrogen atom. This is in contrast to most other bis(TMS)amides (e.g., bis(TMS)- acetamide), which favor the N,O-bis(TMS)imidate isomer. BSF behaves as an N-formamido nucleophile, reacting with the carbonyl group of aldehydes and activated ketones to give N-formyl-O-trimethylsilyl-N,O-acetals. Similarly, reaction with imines (or their precursors) can in some cases give N-formylN,N-acetals. BSF undergoes reactions with a range of other electrophiles including acid chlorides, chloroformate esters, and isocyanates to give a range of interesting products. When treated with organolithium nucleophiles, attack occurs at the carbonyl function, to provide N-silylaldimines after elimination of a silyloxy unit. Such imines are reported to undergo further reactions to give heterocycles. There are also reports of BSF acting as a silylating agent, to give silyl enol ethers, although it is not commonly used for this application.

Preparationchlorotrimethylsilane was added at room temperature to a solution of formamide and triethylamine in dry benzene and the mixture was heated at reflux for 1 h. The reaction mixture was filtered, and the filtrate was evaporated to give a crude oil. This was purified by high-vacuum distillation to afford N,N-bis(trimethylsilyl)formamide (BSF) as an oil in 75% yield.