Synthesis of cyclic analogues of hexamethylenebis(3-pyridine)amide (HMBPA) in a one-pot process

A series of cyclic analogues of hexamethylenebis(3-pyridine)amide was prepared based upon a Ugi-3CR and aza-Diels-Alder reaction as a post-functionalization in a one-pot process. A simple condensation of commercially available diamine and aldehydes followed by isonitrile α-addition provides the oxazole intermediates, finally an aza-Diels-Alder cycloaddition and ring-opening using maleic anhydride provides the desired compounds in modest overall yields in approximately 40 min using microwaves as the heat source and scandium(III) triflate as a catalyst.