The Lewis acid-promoted reactions of alkyl azides with ketones can afford several products. Chief among these result from a Schmidt-like insertion of the azide into the carbon-carbon bond adjacent to the carbonyl group. Alternatively, an acid-promoted rearrangement of the azide to an iminium species can occur, mostly with benzylic azides; the iminium species can then be trapped by the enol of the carbonyl compound in a variation of the Mannich ...