Carbonylative Cyclization of 2-Iodofluorobenzenes and 2-Aminophenols with Recyclable Palladium-Complexed Dendrimers on SBA-15: One-Pot Synthesis of Dibenzoxazepinones

A novel, efficient, and practical route to dibenzoxazepinones has been developed through a one-pot heterogeneous palladium-catalyzed aminocarbonylation/aromatic nucleophilic substitution (S_NAr) sequence starting from readily available 2-iodofluorobenzenes and 2-aminophenols. The carbonylative cyclization reaction proceeds smoothly in dimethyl sulfoxide (DMSO) at 120 °C with 1,8-diazabicyclo(5.4.0)undec-7-ene (DBU) as the base by using a polyamidoamine (PAMAM)-dendronized SBA-15-supported bidentate phosphine-palladium complex [G(1)-2P-Pd(OAc)₂-SBA-15] as the catalyst under 10 bar of CO, yielding a wide variety of dibenzo[<i>b,e</i>][1,4]oxazepin-11(5<i>H</i>)-one derivatives in good to excellent yields. Moreover, this new heterogenized dendritic palladium catalyst has competitive advantages in that it can be facilely recovered by simple filtration in air and recycled more than eight times without any significant loss of activity. The broad substrate scope, high functional group tolerance, and excellent palladium catalyst recyclability of the reaction make this approach a general, efficient, and economical method for the construction of valuable dibenzoxazepinone derivatives.