INTRAMOLECULAR SCHMIDT REACTIONS OF ALKYL AZIDES WITH KETALS AND ENOLETHERS

The ketals or enol ethers of 1,5-azidoketones were converted into lact ams using a two-stage process. Treatment of the ketals and enol ethers with acid (trifluoroacetic acid triflic acid, or trimethylsilyl trifl ate) afforded an oxonium ion which reacted with the tethered azide to give a 1,1-azido-alkoxy intermediate. Bond reorganization led to an im inium ether that was reacted with sodium iodide in acetone to expose t he amide products. Seven intramolecular examples proceeding in yields of 68 to greater than or equal to 95% are reported using dimethyl or d iethyl ketals. Attempts using 1,3-dioxolanes and an intermolecular exa mple are also described.