N-Silylation of amines and amino acid esters under neutral conditions employing TMS-Cl in the presence of zinc dust

An expedient synthetic approach to N-silylamines has been developed. The protocol, using TMS-Cl/zinc dust instead of BSA, is useful for the conversion of amines or amino acid esters to the corresponding silyl derivatives, followed by acylation with an acyl chloride or Fmoc-amino acid chloride to give the corresponding amide or peptide. This procedure, affording products in good to excellent yields, is also efficient for the coupling of sterically hindered amino acids like α,α-dialkylamino acids and NMe-amino acids. Further, the use of an equimolar quantity of organic base, such as Et3N/pyridine, is circumvented.