Metal-Free Oxidation\nof Acceptor–Donor Acylhydrazones\ninto Diazo Compounds Using Phenyl Iododiacetate

Aryl-ester acylhydrazones readily\nreact with phenyl iododiacetate\n(PIDA) in methanol to produce the corresponding α-diazoesters\nwith good to excellent yields (30 examples). The conditions have also\nbeen proven to be efficient in the synthesis of triazolopyridines.\nThe crude mixture containing the diazo compound and acetic acid was\nalso irradiated with low-energy blue LED light for a subsequent one-pot\ninsertion of the in situ-generated carbene with AcOH to afford the\nrespective acetates in high yields.