Arylamine Synthesis Enabled by a Photocatalytic Skeletal-Rearrangement Dehydrogenative Aromatization Strategy

Construction of aromatic compounds from non-aromatic compounds with skeletal edit are appealing yet challenging in organic chemistry. Herein, we report an approach for the synthesis of site-selective substituted arylamines via photocatalyzed C-N coupling/skeletal expansion/dehydrogenative aromatization reaction. A wide variety of primary amines, cyclic and acyclic secondary amines as well as iodomethyl cyclopentanones with diverse substitution patterns are suitable for this strategy, providing an unprecedented and straightforward access to N,N-dialkyl and N-alkyl arylamines. Notably, free amino alcohols undergo selective N-arylation to deliver N-monoarylated amino alcohols. Mechanistic studies show that radical initiated skeletal rearrangement of cyclopentenyl iminiums followed by selective hydrogenative aromatization is a key to success of this strategy. We hope this strategy will inspire more effort to build arylamines and other aromatic compounds from non-aromatic systems.