Amino Acid Derivatives in Organic Synthesis, Part 4 [1]: Facile Synthesis of Heterocycles Containing a Glycine Residue

Pyridines, thiazolopyridines and pyrazolopyrans containing glycinate residue were prepared by reacting N-cyanoacryloglycinate ylidenes with active methylene compounds via a Michael addition - intracyclization synthetic pathway. Simple routes for the synthesis of heterocycles with an amino acid residue were previously reported [1-3] as the incorportation of these residues improves the pharmacokinetics and toxicity of active compounds [4,5]. However, trials to deesterify these residues for coupling purposes were unsuccessful. So, we tried herein new approaches for synthesizing heterocyles carrying one or two glycine moieties with free carboxylic acid group to facilitate further peptide linkage [6] on one hand and on the other one could be able to form metal chelates, a property having a significant output on the toxicological behaviour [7]