N‐Benzyl‐Protection of Amino Acid Derivatives by Reductive Alkylation with α‐Picoline‐Borane.

A convenient method for N-protection of amino acid derivatives with a benzyl group by reductive alkylation of amino acid derivatives with α-picoline-borane is described. Amino acid esters or amino alcohols were treated with aryl aldehydes in methanol/acetic­ acid in the presence of α-picoline-borane to give N-benzyl-protected amino acid derivatives in good yields.