Synthesis of amides from unprotected amino acids by a simultaneous protection–activation strategy using dichlorodialkyl silanes

Reaction of l-phenylalanine (1) with dichlorodimethylsilane or other dichlorosilane derivatives 6b–d and primary amines leads to the formation of amides probably via a cyclic silyl intermediate. It is also possible to use β-amino acids and N-alkylated amino acids (peptoid building blocks) as well as the amino dicarboxylic acid l-aspartic acid. The latter leads to almost exclusive formation of the α-amide.