Cycloaddition of new N-unsubstituted azomethine ylides generated from N-[(trimethylsilyl)methyl]thiocarbamates, synthetic equivalents of nonstabilized alkoxy- or alkylthionitrile ylides

Abstract

The reaction of (trimethylsilyl)methyl isothiocyanate with alcohol in the presence of aluminum alkoxide provides a useful route for the preparation of N-[(trimethylsilyl)methyl]thiocarbamates. The S-methylation of thiocarbamates followed by desilylation generates nonstabilized azomethine ylides having both methylthio and alkoxy groups at the ylide carbon. These azomethine ylides react with electron-deficient carbon-carbon multiples bonds to give formal alkoxynitrile ylide- and/or methylthionitrile ylide-cycloadducts. Thus, the azomethine ylides can be synthetic equivalents of nonstabilized alkoxy- or methylthionitrile ylides that are otherwise relatively inaccessible.