Facile 1,3-diaza-Claisen Rearrangements of Tertiary Allylic Amines Bearing an Electron-Deficient Alkene

Tertiary allylic amines with an electron-deficient alkene react with isocyanates and isothiocyanates to give highly substituted ureas and thioureas arising from formal 1,3-diaza-Claisen rearrangements. Isocyanates and isothiocyanates with strong electron-withdrawing groups are more reactive. Similarly, the data suggest that a stronger electron-withdrawing substituent on the alkene favors a faster reaction, but this may be offset by sterics in the cyclic transition state.