Thiazole and oxazole building blocks for combinatorial synthesis

Article abstract of DOI:10.1016/S0040-4039(99)01654-8

Three thiazole and oxazole containing amino acids were synthesized in good yields by condensation-cyclization. The active functional groups used, a C-terminal imino ester or a C-terminal aldehyde, reacted with both the amino groups and side chains of either serine or cysteine within 5 minutes at rt to form oxazolines or diasteriomeric mixtures of thiazolidines, respectively. The intermediate heterocyclic rings were then dehydrogenated to form the more stable, fully aromatic, rings. Ready availability of N-protected thiazole and oxazole-containing building blocks facilitates the solid-phase synthesis of natural products such as microcin B17 and other peptide-derived natural products that contain 2,4-linked thiazole and oxazole rings.