Intramolecular Heck Route to 5-, 6-, and 7-Membered O-Containing Heterocycles

Significance

Reported is a method to synthesize 2-arylsubstituted tetrahydropyran, tetrahydrofuran and oxepine derivatives via a Pd-catalyzed intra­molecular Heck reaction. The construction of the precursors is achieved from aromatic aldehydes using established indium or Grignard condensation followed by O-allylation. The reported reactions are suitable for substrates with both electron-donating and -withdrawing substituents, except for nitro groups. The scope of the reaction was insufficiently investigated in terms of the different vinylbromides used.