A New and General Route to<i>N</i>-Unsubstituted Azomethine Ylides from<i>N</i>-(Silylmethyl)thioureas: Cycloaddition of Synthetic Equivalents of Nonstabilized Aminonitrile Ylides
by the desilylation generates N-unsubstituted azomethineylides having both methylthio and amino groups at the ylide carbon. These azomethineylides react with electron-deficient olefins to give formal aminonitrile ylide cycloadducts, novel 2-aminopyrrolines. Thus, the azomethineylides can be synthetic equivalents of nonstabilized aminonitrile ylides which are otherwise relatively inaccessible.