Direct α,β-C–H Difunctionalization of Piperidines for the Construction of the <i>N</i>,<i>O</i>-Acetal Skeleton via 1,5-Hydride Transfer

Herein, we describe an unprecedented Lewis acid-catalyzed annulation of phenols with <i>o</i>-aminobenzaldehydes via a cascade coupling/1,5-hydride transfer/cyclization sequence. The α- and β-positions of cyclic amines were functionalized utilizing enamines generated <i>in situ</i>. A series of complex <i>N</i>,<i>O</i>-acetal derivatives are synthesized in moderate to good yields in one step. The methodology features high atom and step economy, excellent diastereoselectivity, and water as the sole byproduct.