The use of bis(trimethylsilyl) acetamide and bis(trimethylsilyl) urea for protection and as control reagents in synthesis

The oxophilicity of silicon allows the efficient protection of a range of hydroxyfunctionalities using either N,O-bis(trimethylsilyl)acetamide (BSA) or N,N-bis(trimethylsilyl)urea (BSU). Three distinct mechanistic pathways are proposed for the reactions of the reagents which explain the mild reaction conditions that can be used to achieve a number of important synthetic transformations. The reactions include examples where improved stereochemical control results from the use of BSA.