Synthesis Of MCM-41-supported Bidentate Phosphine Palladium(O) Complex And Their Application In Organic Synthesis

Diphosphino-functionalized MCM-41 anchored palladium(0) complex (denoted as MCM-41-2P-Pd(0)) was conveniently synthesized from commercially available and cheapγ-aminopropyltriethoxysilane via immobilization on MCM-41, followed by reacting with diphenylphosphinomethanol and palladium chloride, then the reduction with hydrazine hydrate. This palladium complex was characterized by XRD, XPS and elemental analysis.The Heck arylation reaction of styrene, acrylic acid, butyl acrylate, acrylamide with aryl iodides or electron-deficient aryl bromides proceeded very smoothly in the presence of MCM-41-2P-Pd(0) complex to give the corresponding arylation products in excellent yields. Although the reactivity of unactivated aryl bromides was low under the same conditions, the arylation reaction could also take place in the presence of a catalytic amounts of MCM-41-2P-Pd(0) and PPh3 giving the corresponding arylation products in good yields.In order to evaluate the catalytic activity of MCM-41-2P-Pd(0), the Sonogashira reactions of terminal alkynes with aryl iodides were studied.The Sonogashira reactions proceeded smoothly in the presence of a catalytic amounts of MCM-41-2P-Pd(0) and CuI in piperidine at room temperature giving the corresponding coupling products in excellent yields. The Suzuki reactions of arylboronic acids with aryl halides were also studied. The Suzuki reactions of a variety of substituted iodobenzene with arylboronic acids were carried out with a catalytic amounts of MCM-41-2P-Pd(0) using K2CO3 as base in dioxane at 80℃and the reactions proceeded smoothly giving the correspond- ing coupling products in excellent yields. The Suzuki reactions of a variety of aryl bromides with arylboronic acids could also proceed smoothly at 100℃to give the corresponding coupling products in high yields on longer times.The catalytic properties of MCM-41-2P-Pd(II) for Heck carbonylation of aryl halides were studied. The Heck carbonylation reactions of a variety of substituted iodobenzene with aniline or butanol were carried out with a catalytic amounts of MCM-41-2P-Pd(II) and the reactions proceeded smoothly giving the corresponding coupling products in high yields. Although the reactivity of unactivated aryl bromides was low under the same conditions, the arylation reaction could also take place in the presence of a catalytic amounts of MCM-41-2P-Pd(0) and PPh3 giving the correspon- ding Heck carbonylation products in good yields.The catalytic properties of MCM-41-2P-Pd(0) for carbonylative Sonogashira coupling reaction of aryl iodides with terminal alkynes and CO were studied. The carbonylative Sonogashira coupling reaction of terminal alkynes with a variety of aryl iodides with electron-donating substituents in the presence of a catalytic amounts of MCM-41-2P-Pd(0), Et3N as base and CO(1 atm) gives the corresponding alkynyl ketone in good isolated yields after stirring at room temperature for 30-72h. The carbonylative Sonogashira coupling reaction of phenylacetylene with a variety of aryl iodides with electron-withdrawing substituents was slow in the presence of a catalytic amounts of MCM-41-2P-Pd(0) in THF using ammonia water as base at room temper- ature, affording the corresponding coupling products in lower yields on longer times.The novel MCM-41-supported bidentate phosphine palladium(0) complex catalyst can be easily recovered by simple filtration and can be reused many times without loss of activity.