Geometry-Selective Synthesis of <i>E</i> or <i>Z</i> <i>N</i>-Vinyl Ureas (<i>N</i>-Carbamoyl Enamines)
作者:Julien Lefranc、Daniel J. Tetlow、Morgan Donnard、Alberto Minassi、Erik Gálvez、Jonathan Clayden
DOI:10.1021/ol1027442
日期:2011.1.21
N-Vinyl ureas are emerging as a valuable class of compounds with both nucleophilic and electrophilic reactivity. They may be made by capturing the enamine tautomer of an imine with an isocyanate, a reaction which in general leads to the E isomer of the vinyl urea. Deprotonation of such a vinyl urea, or of an allyl urea, generates a dipole stabilized Z-allyl anion which may be protonated to return the Z-vinyl urea. Isomerization of an allyl urea with a Ru complex provides an alternative route to E-vinyl ureas.