Novel one pot synthesis of azolo[1,5-a]pyridines from Viehe’s salts

We have developed a practical procedure for the synthesis of polyfunctional azolo[1,5-a]pyridines via the reactive species generated in situ from N-substituted lactams and Viehe’s salt. The reaction is regioselective with respect to the nucleophilic addition of bis-anions derived from methyl azolyl acetates. The described protocol allowed for the introduction of three elements of diversity into the targeted molecules, including substituents originating from the (i) nucleophile input, (ii) lactam ring, and (iii) nucleophilic aromatic displacement (S_NAr) of the NMe₂ group with amines. A short reaction sequence, good yields of title compounds (44-69%), as well as their ready isolation, and purification are the distinct advantages of the reported protocol.