Palladium-Catalyzed Sequential Alkylation−Alkenylation Reactions. Application to the Synthesis of 2-Substituted-4-Benzoxepines and 2,5-Disubstituted-4-Benzoxepines
journal contributionposted on 07.05.2002, 00:00 by Mark Lautens, Jean-François Paquin, Sandrine Piguel
The synthesis of 2-substituted-4-benzoxepines and 2,5-disubstituted-4-benzoxepines from aryl iodides and bromoenoates is described. This methodology is based on a palladium-catalyzed aromatic substitution followed by an intramolecular Heck sequence. Under the reaction conditions (Pd(OAc)2 (10 mol %), tri-2-furylphosphine (20 mol %), norbornene (2 equiv), Cs2CO3 (2 equiv), CH3CN, 85 °C), moderate to excellent yields of benzoxepines bearing numerous substituents (Me, F, Cl, etc.) are obtained.