Brønsted Acid Catalyzed Dearomatization by Intramolecular Hydroalkoxylation/Claisen Rearrangement: Diastereo‐ and Enantioselective Synthesis of Spirolactams

Described herein is a novel Brønsted acid catalyzed intramolecular hydroalkoxylation/Claisen rearrangement, allowing the practical and atom‐economic synthesis of a range of valuable spirolactams from readily available ynamides in generally good to excellent yields with excellent diastereoselectivities and broad substrate scope. Importantly, an unexpected dearomatization of nonactivated arenes and heteroaromatic compounds is involved in this tandem sequence. Moreover, an asymmetric version of this tandem cyclization was also achieved by efficient kinetic resolution by chiral phosphoric acid catalysis. In addition, the [3,3]‐rearrangement is shown to be kinetically preferred over the related [1,3]‐rearrangement by theoretical calculations. A Brønsted acid catalyzed intramolecular hydroalkoxylation/Claisen rearrangement is disclosed that involves an unexpected dearomatization of nonactivated arenes and heteroaromatic compounds and allows the practical and atom‐economic synthesis of various valuable spirolactams. Moreover, the asymmetric version of this tandem cyclization is also achieved via kinetic resolution by chiral phosphoric acid catalysis.