Synthesis of Imidazo[1,2-a]pyridines via Multicomponent GBBR Using α-isocyanoacetamides？

Six novel imidazo[1,2- a]pyridines were synthesized by Groebke–Blackburn–Bienayme？ reactions (GBBRs) under eco-friendly conditions (10 mol% ammonium chloride catalyst in EtOH at room temperature) with moderate to good yields (76–44%) using 2-isocyano-1-morpholino-3-phenylpropan-1-one. This is the first successful use of this type of α-isocyanoacetamide in a GBBR, as these reactive isonitriles readily undergo ring-chain tautomerization, as reported in other IMCRs (isonitrile-based multicomponent reactions). The product structures contain a peptidomimetic imidazo[1,2- a]pyridine scaffold linked to an α-aminomorpholide and are of interest to medicinal chemists