Stereospecific Synthesis of ( E )‑5-Tetrasubstituted-ylidene-3,5-dihydro‑4 H ‑imidazol-4-ones

A stereospecific synthesis of (E)-5-tetrasubstituted-ylidene-3,5-dihydro-4H-imidazol-4-one derivatives is demonstrated through a cascade process by combination of a Michael addition and Boulton–Katritzky rearrangement. The method provides a simple and efficient approach for the synthesis of (E)-5-tetrasubstituted-ylidene-3,5-dihydro-4H-imidazol-4-ones from the reactions of N-(isoxazol-3-yl)-propiolamides or N-(1,2,4-oxadiazo-3-yl) propiolamides with N or C nucleophiles.