A Facile Approach to Oximes and Ethers by a Tandem NO+‐Initiated Semipinacol Rearrangement and H‐Elimination

An efficient oximation method has been developed on the basis of NO+‐initiated semipinacol rearrangement and subsequent proton elimination. The procedure enabled the rapid construction of a series of oximes and oxime ethers with spiro quaternary stereocenters from allylic silyl ethers. Additional features of this reaction include wide substrate tolerance as well as the commercial availability of the safe nitrosation reagent NOBF4. The key N‐heterotricyclic cores of three natural alkaloids, tuberostemoninol B, (+)‐quebrachidine, and an insecticide, were also constructed efficiently by this method. Straight to the core: An oximation method based on NO+‐initiated semipinacol rearrangement and subsequent proton elimination enabled the rapid construction of a series of spirocyclic oximes and oxime ethers with quaternary stereocenters from allylic silyl ethers (see scheme). The key N‐heterotricyclic cores of three natural alkaloids, tuberostemoninol B, (+)‐quebrachidine, and an insecticide, were also constructed efficiently by this method.