N-(p-Ethynylbenzoyl) derivatives of amino acid and dipeptide methyl esters – Synthesis and structural study

A series of N-(p-ethynylbenzoyl) derivatives (1–4) of the amino acids glycine and l-alanine as well as the dipeptides glycylglycine and l-alanylglycine has been synthesized via a two-step reaction sequence including the reaction of an appropriate N-(p-bromobenzoyl) precursor with trimethylsilylacetylene followed by deprotection of the trimethylsilyl protecting group, respectively. X-ray crystal structures of the amino acid and dipeptide methyl esters 1–4 are reported. The amide and peptide bonds within each molecular structure are planar and adopt the trans-configuration. The packing structures are governed by NH⋯O interactions leading to the formation of characteristic strand motifs. Further stabilization results from weaker CH⋯O and CH⋯π contacts.