posted on 2021-06-24, 19:22authored byXandro Vidal, José Luis Mascareñas, Moisés Gulías
Cycloaddition
reactions are among the most practical strategies
to assemble cyclic products; however, they usually require the presence
of reactive functional groups in the reactants. Here, we report a
palladium-catalyzed formal (4 + 2) cycloaddition that involves the
activation of C(sp3)–H bonds and provides a direct,
unconventional entry to tetrahydroquinoline skeletons. The reaction
utilizes amidotolyl precursors and allenes as annulation partners,
and is catalyzed by Pd(II) precursors in combination with specific N-acetylated amino acid ligands. The reactivity can be extended
to ortho-methyl benzylamides, which provide for the
assembly of appealing tetrahydro-2-benzazepines in a formal (5 + 2)
annulation process.