Facile N-Derivatization of α-Amino Esters and Amides via Benzotriazolylmethyl Derivatives

α-(N-Substituted amino)esters were prepared in a two-step procedure from available unsubstituted α-amino esters. α-Amino esters are first converted into the corresponding <i>N</i>-benzotriazolylmethyl derivatives; in the second step, the benzotriazole group is substituted by various nucleophiles with or without the presence of a Lewis acid to give substituted α-amino esters in high overall yield under mild conditions with no signs of racemization. Boc-protected amino acids were converted into α-amino amides; subsequent deprotection allowed the conversion into N-substituted derivatives analogously to the α-amino esters, without racemization in high yields under mild conditions.