Cycloaddition of new N-unsubstituted azomethine ylides generated from N-(trimethylsilylmethyl)thioureas to electron-deficient olefins, acetylenes andaldehydes, synthetic equivalents of nonstabilized aminonitrile ylides

The S-methylation of N-(trimethylsilylmethyl)thioureas and the subsequent d esilylation of the silylmethyl group generates N-unsubstituted azomethine y lides having both methylthio and amino groups at the ylide carbon. These az omethine ylides undergo successful cycloaddition to electron-deficient olef ins, acetylenes and aldehydes. As the methylthio group is eliminated under the reaction conditions to produce the corresponding pyrrolines, pyrroles a nd 2-oxazolines bearing the amino group at 2-position, these azomethine yli des can be synthetic equivalents of nonstabilized aminonitrile ylides that are otherwise relatively inaccessible. (C) 2000 Elsevier Science Ltd. All r ights reserved.