Introduction
N,O -Bis(trimethylsilyl)acetamide (BSA) is a colorless liquid with a boiling point of
71–73 °C/35 mmHg. It is extremely moisture sensitive and can also be rapidly contaminated
with trimethylsilylacetamide and acetamide. The reagent is commercially available
and can be prepared from acetamide with an excess of triethylamine and chlorotrimethylsilane
(Scheme [1 ]).[
1
] Since the early use of BSA in chromatographic analysis for the preparation of volatile
trimethylsilyl derivatives, it has also proved to be useful in many synthetic applications.[
2
] At first, BSA has been used as a powerful silylating agent for the protection of
amines, amides, carboxylic acids, alcohols, enols and phenols. In these cases, BSA
is an attractive alternative to other silylating agents, such as trimethylsilyl chloride.
Indeed, the reaction conditions are generally mild and neutral, and the byproducts
are sufficiently volatile to be easily removed from the reaction mixture by evaporation
under reduced pressure. It has also been used as a Brønsted base precursor in Tsuji–Trost
reactions. More recently, it has been used to activate various functional groups during
the formation of nucleosides, peptides and heterocycles to name but a few.
Scheme 1 Synthesis of N,O -Bis(trimethylsilyl)acetamide