Diazoacetic acid esters are important intermediates in drug and agrochemical synthesis, but their preparation typically requires hazardous diazomethane. Researchers from the Tokyo University of Science developed a safer method using a Michael addition-mediated azide-to-diazo conversion. By pretreating 2-azidoacrylic acid esters with a bulky phosphine followed by nucleophile addition, they produced β-heteroatom-substituted diazo esters without toxic precursors. This simpler approach offers a practical and flexible route to access diverse organonitrogen compounds.