Carbonylative Cyclization\nof 2‑Iodofluorobenzenes\nand 2‑Aminophenols with Recyclable Palladium-Complexed Dendrimers\non SBA-15: One-Pot Synthesis of Dibenzoxazepinones

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