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

The reaction of (trimethylsilyl)methyl isothiocyanate with alcohol in the p resence of aluminum alkoxide provides a useful route for the preparation of N- [(trimethylsilyl) methyl] thiocarbamates. The S-methylation of thiocarb amates followed by desilylation generates nonstabilized azomethine ylides h aving both methylthio and alkoxy groups at the ylide carbon. These azomethi ne ylides react with electron-deficient carbon-carbon multiples bonds to gi ve 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 inaccessi ble.